I was disappointed when I started using Quicktime Pro 7 and discovered that I couldn't add Director, Performers, Producer or Writer annotations to my movies. Only basic Annotations could be added or modified using the Show Movie Properties Option.
When I finally upgraded to Tiger, I discovered that you can use the Automator action named Set Movie Annotations (in the QuickTime Player Library) to add this metadata to your movie files.
Unfortunately, Spotlight doesn't index these advanced QuickTime attributes, but at least they're there.
Mac OS X Hints
http://hints.macworld.com/article.php?story=2005101712363877