QuickTime is an excellent movie viewer application that uses the latest streaming technology to access instant content on the Web.
This viewer plays clips in almost every movie format, and is the only player that will work with some exclusive Apple formats (*.mov).

Features:

Sports a small and attractive interface.
The range of formats this viewer can open is amazing.
Includes in the installation browser plug-ins to heighten your QuickTime experience on the web.
I fell in love with this viewer the first I ran it. If you don't have it, it should be on your Christmas download list to get, it's certainly worth the download. In fact, it's a "must download." Watch for updates, Apple has done an excellent job.
Requirements
Microsoft DirectX