Just to let you know, there are still problems with GMA950 video cards (used by the Mac Mini). I changed some of the calls from glMultiTexCoord2f to glMultiTexCoord2fARB, but it turns out I missed a bunch more.
On the other hand, I have successfully played high definition MKV videos on my wife’s iMac, which has the ATI Radeon HD2400. NOTE: You must make sure that the video resolution settings *match* between the video settings and the appearance settings (I used 720p for testing). Otherwise you will end up with a white screen, lack of video, and a completely unexpected audit by the IRS.
Version 0.0.3, available here, has one small change, which may or not make any difference at all. It was suggested by the ever-helpful d4rk as a solution to an OpenGL threading issue I was seeing with the debug display turned on.