I have no problems playing mpeg2 b/c I have QT Pro which came as part of another softw package. But the QT MPeg2 playback plug-in is a separate commercial product. By the way have you turned all your QT plug-ins on. Go to System Prefs>QT>Click Plug-in Tab & at bottom press MIME Settings. Tick all options.

So for mpeg2 movies it looks as though you're stuck with either vlc or mplayer.

Oh I just thought. It might be wise to get yourself some xtra plug-ins for QT. For DivX go to http://www.divxmovies.com/codec/ For 3ivx go to http://www.3ivx.com/ & go to dwnld page & look on top right of page. I should also have mentioned Xvid which you'll find at the divx site I gave you.