See also the article : "Video Overlay settings at zero after changing scheme" from intel
This solved my problem. It was odd because I had audio but no video in ALL video players. It took me quite some time to figure mine out. And IT wasn't even a codec problem or anything wrong with the various players I tried to use.
Obviously my computer has a intel graphics driver, but you may have a similar problem. Worth a shot. of late, I have been switching schemes (schemes for screen display from laptop to external monitor) I was using a HD TV as a second screen on extended settings and then switching back all the time.
http://www.intel.com/support/graphics/i ... 029329.htm