You can't view it because you don't have the codec that was used to encode the video.
You do, however, have the required codec for the sound aspect.
This situation is a bitch, because any codecs can be used within an AVI.
Download all of the Intel Indeo codecs from
Apple, and install them. All of them - they aren't different versions of the one codec, but different codecs.
Now, go get
DivX Player and Windows Media Player 6.3, which will play most AVI's.