Problem with internet video

Hi,
I use windows XP. Let me go to the problem. When I try to see Videos, eg. BBC News or other channels etc. from internet the movie window will come there and the sound is there as well. But the video is not shown there. A green screen is appeared instead of video. But if I watch some clippings from You Tube, there is no problem everything is fine. I can watch a movie from a CD as well. The only problem faced is the first one I stated earlier. This problem started recently and before it was ok.

I am looking to hear an advise from any experts.

Thanks

Geo