Umm a mpeg or mpg (same thing) are huge use .avi much smaller if you eed help playing them go to www.3ivx.com any way for the mpeg go into your contole pannel (apple menue if you have 9 or below) click on quicktime settings then a window willl pop up go down to update and update everything. that should do the trick.

p.s. itues is a mp3 wav/aiff player/ripper that would get you no ware beucse you are trying to play a movie.