well mate, you cant just play video over html, but you can embed a video in an html page...
(hopefully I havent got the wrong end of the stick!)
HTML is a markup language, thats defined by tags. You are limited to what you can do with it by what tags there are, this includes the embed tag so you can use other sorts of media in an html page, but whatever you embed needs to be understood by the computer that will read it. What this means is that if you use windows media then your mac and linux users are stuffed, so perhaps shockwave flash is the answer? maybe quicktime - thats a popular codec?