You need to download a program called Camtasia (free trial, set the date back and it will work "forever"), and I think it installs an AVI player plugin for WMP10. I am not sure, but that should make it work, it did it for me, plus its a REALLY handy program!!
Be sure to download it from the manufacturer or whatever site, not some 3rd party place, unless download.com has it...
Yan