Silverlight Live Videos Streaming

Question

Hey,
 I am working on a live session telecast system, were viewers enroll to watch a live session, conducted by the presenter, There is a facility to the presenter to push videos and presentations during the live session, when the presenter does that, our silverlight control doesn't work appropriatly, all other viewers report, sliced vidoes and too much time in buffering, if there is any suggestion from anyone of u kindly share with me, It will be highly appreciated.
Thanx in advance
Saddal