Recently I tried to present a large movie to a TV through my PowerBook 667. Most of the movie played fine, but there was a lot of noticeable skipping and stuttering during parts where there was a lot of movement on the screen.
After some tweaking in the video and sound properties in QuickTime Player, I found that you can preload the video and sound into memory. Select Movie -> Get Movie Properties, then select Video Track under the left-side pop-up menu and Preload on the right side pop-up menu, and then check the Preload button. Repeat for the Sound Track (left-side pop-up). this reduced the skipping by a large amount.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20030127054928423