So simple,but here it is anyway. Now that the iTunes Music Store has videos and iTunes supports video playback, you can use a Smart Playlist to track them all:
Create a new Smart Playlist with these settings: Kind > Contains > Quicktime, and you've got them all. One caveat: if you have other QuickTime files in your Library, they'll show up as well. Cool, easy, and your own MTV.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20050518014610857