It's been since Ubuntu 11.04 that a regression appeared which causess all video playback (which uses hardware acceleration) to have all the colors messed up, at least on NVidia graphics cards. The issue was already widely known when I was apparently (and surprisingly) the first one to report it in Launchpad, and not only it hasn't been fixed but it hasn't got the least attention: it hasn't been assigned nor has it even been decided its "importance" (which is not very difficult to decide). https://bugs.launchpad.net/ubuntu/+source/nvidia-graphics-drivers/+bug/862831
There are workarounds for local video file playback (applying color settings to compensate for the wrong colors) but they must be done for every player, and not all players have this option; plus for other things such as video streaming from web (e.g. YOUTUBE) there's no workaround other than disabling video hardware acceleration, which has an unacceptable performance cost.
The question is, is this being addressed or doen't anybody give a ** that you can't use Ubuntu for anything video-related?