Firefox not playing videos

Generally I save videos to watch them but some sites insist on watching videos in a webpage. For some reason my firefox can't play them. It says its missing a plugin. When I click to download it it says it can't find one. So what plugin am I missing? It wont play any media in a window I don't think. I am using media player classic and real alternatives for quicktime and real.

>>6
Yes because switching from a browser that can use 1GB+ of RAM to itself, relies on the use of insecure plugins for ANY functionality and has a bunch of furryfag followers, to a squck, stable, reliable browser with less memory usage and all the functionality you need (including IRC, mail and torrent) in one package? That's definately a bad choice.