Playing Video with WMP 11

I am having trouble playing the videos using Windows Media Player 11.  I hear the sound great, but have no video.  I have updated all browsers, plug ins  etc, but still have the issue.  Also, I can see and hear the video fine in Quicktime. 

Are there any other educators that are running into the same issues?  I have Vista, if that may help.  Any suggestions would be greatly appreciated.

Tina