Ok, it works, but you better have a powerful codec. Honestly, AVI is NOT the wrapper for videos posted to a forum. It's typically uncompressed and HUGE! MP4 would be the better route.
The forum only allows 4.7 meg AVIs, and what I just uploaded is 1/2 that at 2 meg, and it is only 6 seconds long. So, you'll be lucky to get more than 10 seconds with typical compression on an AVI. It'll be better to go to youtube or Vimeo.