QuickTime ® is a standard file format created by Apple ® for storing common digital media types such as audio and video. When you choose QuickTime (*.mov) as the Save As Type, your animation is saved as a .mov file.
You can export animations to .mov for both rendering and previews. You can also export audio if an audio track is present in Track View. You can download the QuickTime movie player from http://www.apple.com/quicktime/download.
When you create a new QuickTime file or choose Setup for an existing one, you see a dialog that is typically titled Compression Settings. This dialog is provided by the QuickTime codec installed with your system, and can change depending on the version of QuickTime you've installed.