Quartz Composer's built-in "Export" command takes the composition and wraps it in a special kind of QuickTime movie — in order to play this movie back, you need a Mac, you need QuickTime Player version 7, and you can't use any "unsafe" plugins (i.e., almost all 3rd-party plugins). So, even when it works, it's of limited utility.
There are a few other options for taking the visual rendered output of a Quartz Composition and turning it into a normal movie (which you can share with non-Mac users) —
- Use qtzrendang — it renders composition frames to a movie file.
- Use Kineme QuartzCrystal — it renders composition frames to a movie file, with additional features like antialiasing and motion blur. (*)
- Put your composition inside a
Render In Image
patch, and feed the output to the Movie Exporter Plugin.
(*) Disclosure: I'm one of the developers of this software.