Peter Maurer is an interesting Mac developer. He's a German medical student who also happens to write really excellent Mac software in his spare time, probably most importantly Butler. He's already developed and sold several excellent apps such as TextExpander (was Textpander), MenuCalendarClock (was Calendarclock), and now yFlicks (was Clip Show); however, instead of selling yFlicks to another company this time he's decided to start his own: Many Tricks. He has always offered free licenses to people who have contributed to the pre-commercial versions of his software and he continues this laudable practice with yFlicks. Those who contributed to Maurer for Clip Show prior to Jan 12, 2007 are eligible for a free license for yFlicks.
yFlicks is a video player based on QuickTime. In some ways it looks sort of like an iPhoto for videos, allowing you to "play videos in fullscreen mode, organize your videos in groups, search them, rate them, and browse them in preview mode." In addition, like TubeSock and Tubular it allows you (with Perian) to download videos from YourTube or Google and then export them to your iPod.
yFlicks is €15 (~$19) and a demo is available.
[Edit: reverted to a language I actually know and clarified upgrade policy]