sobre un navegador

Question

estoy realizando un navegador y si me reproduce el problema es que al cerrar el navegador la el video de youtube sigue reproduciendoce como hago para que se cierre

mi codigo lo tengo haci

Imports System.Net
Imports System.Data.OleDb
Imports System.Xml
Public Class NAVEGADOR

#Region "enumerados"

    Private Enum Exec
        OLECMDID_OPTICAL_ZOOM = 63
        OLECMID_CUT = 11
        OLECMID_COPY = 12
        OLECMID_PASTE = 13
        OLECMDID_DELETE = 33
        OLECMDID_SELECTALL = 17
        OLECMDID_FIND = 32
    End Enum

    Private Enum ExecOpt
        OLECMDEXECOPT_DODEFAULT = 0
        OLECMDEXECOPT_PROMPTUSER = 1
        OLECMDEXECOPT_DONPROMPTUSER = 2
        OLECMDEXECOPT_SHOWHELP = 3
    End Enum
#End Region

#Region "Variables"
    Dim i As Integer = 0
    Dim valorZoom As String = 100
#End Region


#Region "FuncionesAgregadas"
    'Procedimiento NuevaPestaña 
    'modo = 0 ; entonces irá a la página de inicio
    'modo = 1; entonces duplicara la pestaña
    Public Sub NuevaPestaña(ByVal modo As Byte, url As String)
        Dim browser As New WebBrowser
        TabControl1.TabPages.Add("Nueva pestaña")
        TabControl1.SelectTab(i)
        browser.Name = "Navegador"
        browser.Dock = DockStyle.Fill
        TabControl1.SelectedTab.Controls.Add(browser)
        AddHandler browser.ProgressChanged, AddressOf Loading
        AddHandler browser.DocumentCompleted, AddressOf Done
        i = i + 1
        CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).ScriptErrorsSuppressed = True
        If modo = 0 Then
            CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).Navigate(leerHome)
        Else
            CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).Navigate(url)
        End If

    End Sub

    Function leerHome()
        Dim myXmlDocument As New XmlDocument()
        myXmlDocument.Load(My.Application.Info.DirectoryPath + "\home.xml")
        Dim node As XmlNode
        node = myXmlDocument.DocumentElement
        Return node.ChildNodes.Item(0).InnerText
    End Function

    Private Sub Loading(ByVal sender As Object, ByVal e As Windows.Forms.WebBrowserProgressChangedEventArgs)
        Try
            progreso_ProgressBar.Maximum = e.MaximumProgress
            progreso_ProgressBar.Value = e.CurrentProgress
        Catch ex As Exception

        End Try
    End Sub

    Private Sub Done(ByVal sender As Object, ByVal e As Windows.Forms.WebBrowserDocumentCompletedEventArgs)
        TabControl1.SelectedTab.Text = CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).DocumentTitle
        urlTextBox.Text = CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).Url.ToString
    End Sub

    Private Sub HacerZoom(ByVal valor As String)
        Try
            Dim res As Object = Nothing
            Dim MyWeb As Object
            MyWeb = CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).ActiveXInstance
            MyWeb.ExecWB(Exec.OLECMDID_OPTICAL_ZOOM, ExecOpt.OLECMDEXECOPT_PROMPTUSER, Integer.Parse(valor))
        Catch ex As Exception
            MessageBox.Show(ex.Message.ToString)
        End Try
    End Sub
#End Region





#Region "OtrosEventos"

    Private Sub TabControl1_Selected(ByVal sender As System.Object, ByVal e As System.Windows.Forms.TabControlEventArgs)
        Try
            urlTextBox.Text = CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).Url.ToString
        Catch ex As Exception
        End Try
    End Sub

    Private Sub ComboBox1_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles ComboBox1.SelectedIndexChanged

    End Sub

    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        estadoLabel.Text = CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).StatusText
    End Sub

#End Region

#Region "EventoLoad"
    Private Sub Principal_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        TabControl1.TabPages.Add("Nueva pestaña")
        Dim browser As New WebBrowser
        browser.Name = "Navegador"
        browser.Dock = DockStyle.Fill
        TabControl1.SelectedTab.Controls.Add(browser)
        CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).ScriptErrorsSuppressed = True
        CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).Navigate(leerHome)
        AddHandler browser.ProgressChanged, AddressOf Loading
        AddHandler browser.DocumentCompleted, AddressOf Done
        i = i + 1
    End Sub
#End Region

#Region "MenuArchivo"
    Private Sub AñadirPestañaMI_Click(sender As System.Object, e As System.EventArgs) Handles AñadirPestañaMI.Click
        NuevaPestaña(0, Nothing)
    End Sub

    Private Sub DuplicarPestañaMI_Click(sender As System.Object, e As System.EventArgs) Handles DuplicarPestañaMI.Click
        NuevaPestaña(1, urlTextBox.Text)
    End Sub

    Private Sub QuitarPestañaMI_Click(sender As System.Object, e As System.EventArgs) Handles QuitarPestañaMI.Click
        If Not TabControl1.TabPages.Count = 1 Then
            'Liberamos los recursos usados por el control 
            CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).Dispose()
            'Removemos el tabPage del tabcontrol
            TabControl1.TabPages.RemoveAt(TabControl1.SelectedIndex)
            'Actualizamos el tab seleccionado 
            TabControl1.SelectTab(TabControl1.TabPages.Count - 1)
            i = i - 1
        End If
    End Sub

    Private Sub NuevaVentanaMI_Click(sender As System.Object, e As System.EventArgs) Handles NuevaVentanaMI.Click
        Dim nueva As New PORTADA
        nueva.StartPosition = FormStartPosition.CenterParent
        nueva.Show()
    End Sub

    Private Sub AbrirMI_Click(sender As System.Object, e As System.EventArgs) Handles AbrirMI.Click
        OpenFileDialog1.Title = "Abrir archivo"
        OpenFileDialog1.FileName = ""
        OpenFileDialog1.Filter = "Paginas web(*.html)|*.html|Paginas web(*.mth)|*.mht|Paginas web(*.aspx)|*.aspx"
        OpenFileDialog1.ShowDialog()
        Dim url As String = OpenFileDialog1.FileName
        CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).Navigate(url)
        urlTextBox.Text = url
    End Sub

    Private Sub GuardarComoMI_Click(sender As System.Object, e As System.EventArgs) Handles GuardarComoMI.Click
        CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).ShowSaveAsDialog()
    End Sub

    Private Sub ConfigurarPaginaMI_Click(sender As System.Object, e As System.EventArgs) Handles ConfigurarPaginaMI.Click
        CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).ShowPageSetupDialog()
    End Sub


    Private Sub VistaPreviaMI_Click(sender As System.Object, e As System.EventArgs) Handles VistaPreviaMI.Click
        CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).ShowPrintPreviewDialog()
    End Sub

    Private Sub ImprimirMI_Click(sender As System.Object, e As System.EventArgs) Handles ImprimirMI.Click
        CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).ShowPrintDialog()
    End Sub

    Private Sub PropiedadesMI_Click(sender As System.Object, e As System.EventArgs) Handles PropiedadesMI.Click
        CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).ShowPropertiesDialog()
    End Sub

    Private Sub SalirMI_Click(sender As System.Object, e As System.EventArgs)
        Me.Close()
    End Sub
#End Region

#Region "MenuEdicion"
    Private Sub CortarMI_Click(sender As System.Object, e As System.EventArgs) Handles CortarMI.Click
        Dim MyWeb As Object
        MyWeb = CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).ActiveXInstance
        MyWeb.ExecWB(Exec.OLECMID_CUT, ExecOpt.OLECMDEXECOPT_DONPROMPTUSER)
    End Sub

    Private Sub CopiarMI_Click(sender As System.Object, e As System.EventArgs) Handles CopiarMI.Click
        Dim MyWeb As Object
        MyWeb = CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).ActiveXInstance
        MyWeb.ExecWB(Exec.OLECMID_COPY, ExecOpt.OLECMDEXECOPT_DONPROMPTUSER)
    End Sub

    Private Sub PegarMI_Click(sender As System.Object, e As System.EventArgs) Handles PegarMI.Click
        Dim MyWeb As Object
        MyWeb = CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).ActiveXInstance
        MyWeb.ExecWB(Exec.OLECMID_PASTE, ExecOpt.OLECMDEXECOPT_DONPROMPTUSER)
    End Sub

    Private Sub BorrarMI_Click(sender As System.Object, e As System.EventArgs) Handles BorrarMI.Click
        Try
            Dim res As Object = Nothing
            Dim MyWeb As Object
            MyWeb = CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).ActiveXInstance
            MyWeb.ExecWB(Exec.OLECMDID_DELETE, ExecOpt.OLECMDEXECOPT_DONPROMPTUSER)
        Catch ex As Exception
            MessageBox.Show(ex.Message.ToString)
        End Try
    End Sub

    Private Sub BuscarMI_Click(sender As System.Object, e As System.EventArgs) Handles BuscarMI.Click
        Dim MyWeb As Object
        MyWeb = CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).ActiveXInstance
        MyWeb.ExecWB(Exec.OLECMDID_FIND, ExecOpt.OLECMDEXECOPT_PROMPTUSER)
    End Sub

    Private Sub SeleccionarTodoMI_Click(sender As System.Object, e As System.EventArgs) Handles SeleccionarTodoMI.Click
        Dim MyWeb As Object
        MyWeb = CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).ActiveXInstance
        MyWeb.ExecWB(Exec.OLECMDID_SELECTALL, ExecOpt.OLECMDEXECOPT_DONPROMPTUSER)
    End Sub
#End Region

#Region "MenuVer"
    Private Sub AumentarZoomMI_Click(sender As System.Object, e As System.EventArgs) Handles AumentarZoomMI.Click
        If valorZoom = 1000 Then
            Return
        End If
        valorZoom += 25
        ComboBox1.Text = valorZoom.ToString + "%"
        HacerZoom(valorZoom)
    End Sub

    Private Sub DisminuirZoomMI_Click(sender As System.Object, e As System.EventArgs) Handles DisminuirZoomMI.Click
        If valorZoom = 25 Then
            Return
        End If
        valorZoom -= 25
        ComboBox1.Text = valorZoom.ToString + "%"
        HacerZoom(valorZoom)
    End Sub

    Private Sub PaginaDeInicioMI_Click(sender As System.Object, e As System.EventArgs) Handles PaginaDeInicioMI.Click
        CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).GoHome()
    End Sub

    Private Sub PaginaActualMI_Click(sender As System.Object, e As System.EventArgs) Handles PaginaActualMI.Click
        CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).Navigate(urlTextBox.Text)
    End Sub
    Private Sub DetenerMI_Click(sender As System.Object, e As System.EventArgs) Handles DetenerMI.Click
        CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).Stop()
    End Sub

    Private Sub ActualizarMI_Click(sender As System.Object, e As System.EventArgs) Handles ActualizarMI.Click
        CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).Refresh()
    End Sub



#End Region


    Private Sub Button8_Click(sender As System.Object, e As System.EventArgs) Handles Button8.Click
        PORTADA.Show()
        Me.Hide()
    End Sub

    Private Sub TabControl1_SelectedIndexChanged(sender As System.Object, e As System.EventArgs) Handles TabControl1.SelectedIndexChanged

    End Sub

    Private Sub HomeBtn_Click(sender As System.Object, e As System.EventArgs) Handles HomeBtn.Click
        CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).GoHome()
    End Sub


    Private Sub AtrasBtn_Click(sender As System.Object, e As System.EventArgs) Handles AtrasBtn.Click
        CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).GoBack()
    End Sub

    Private Sub AdelanteBtn_Click(sender As System.Object, e As System.EventArgs) Handles AdelanteBtn.Click
        CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).GoForward()
    End Sub

    Private Sub ActualizarBtn_Click(sender As System.Object, e As System.EventArgs) Handles ActualizarBtn.Click
        CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).Refresh()
    End Sub

    Private Sub GoBtn_Click(sender As System.Object, e As System.EventArgs) Handles GoBtn.Click
        ''Si el campo URL esta vacio
        If urlTextBox.Text.Trim(" ") = "" Then
            Return
        End If
        'Navego a la pagina web
        CType(TabControl1.SelectedTab.Controls.Item(0), WebBrowser).Navigate(urlTextBox.Text)

    End Sub

    Private Sub urlTextBox_TextChanged(sender As System.Object, e As System.EventArgs) Handles urlTextBox.TextChanged

    End Sub


End Class