You will need a DivX codec to see some of the videos encoded with it.
The codec allows videos to have a greater frame rate (10 frames per second instead of my usual 7 as before) encoded in smaller or equivalent file sizes at up to half the usual encoding time.
The version of the codec for Macintosh computers can be downloaded from this page. For all supported platforms, check this page. Linux and BeOS are included.
To install the 570KB codec for computers running Windows 95 or above:
Afterwards you should be able to play back the video files without a problem.