Normally to play qucktime movies on a PC you need QuickTime installed on that computer, it's not installed by default.
You can get it for free from Apple.com

However, if you're expecting anyone to be able to view it (who might not have quicktime installed), you should probably re-encode the video as an avi for PC users. I think the QuickTime Pro player on a Mac can do this, or there's probably another tool that can convert to avi.