But i can answer you still..
Save, at first you need a video-hoster.. http://www.youtube.com is a very good page..
When you have uploaded you video clip from there, you’ll just refere it from you post..
like this [youtube=http: //www.youtube.com/watch?v=Ahx-IBNFALE]
(just without the “spaces”)
THATs SOME SIMPLE HTML.. all you have to do is insert a link :)