If you have mplayer installed, try entering "mplayer -vo help" to list the various video output drivers.
Some to try are:
x11 X11 ( XImage/Shm )
gl X11 (OpenGL)
gl2 X11 (OpenGL) - multiple textures version
sdl SDL YUV/RGB/BGR renderer (SDL v1.1.7+ only!)nd
Try to play the videos with different output drivers. E.G. mplayer -ao xv video.mpg
The mplayer and gmplayer programs will look in a configuration file which may indicate a video output driver that doesn't work for you.
Make sure you try "mplayer -vo gl2 <video>". If it doesn't work, it could indicate a problem with the GL video drivers. I think that other drivers could be effected if you use compositing. I had a similar problem when compiz was new. Updating my nvideo drivers fixed the problem, if I am remembering correctly.
Last edited by jschiwal; 07-13-2009 at 08:30 PM.