DownloaError error#1001 in control 'SilverlightStreamingMediaPlayer1'

I wanted to play with the Silverlight Streaming Server control that's part of the Live Tools for Visual Studio. When i went to run my application I got the following error: Sys.InvalidOperationExceptoin: DownloaError error#1001 in control 'SilverlightStreamingMediaPlayer1': AG_E_UNKNOWN_ERROR I tried both the Dec CTP and the Feb CTP with the same error. Turns out you can't use a videos that were uploaded using the new "Manage Video" option, only applications. So I've switched back to using videos uploaded as applications and it works a treat :)