Troubleshooting - Huge video files
By default Muvizu:Play uses an Uncompressed codec, as this is the codec that is available on all computers. It does mean that video files created with the Uncompressed codec will be extremely large.
Reduce your video size by using a codec that specialises in compressing video data. A good codec to start with is XVid: http://www.xvid.org
If you video is broken, have a read of this article for more information on the 2GB AVI file size