Why cant I play video from web pages with my Firefox?

[Daliman]

I purchased a new computer, and DL'd Firefox for it, and now, when I go to web pages like break.com, I can't play the videos on it, even though I never had any problem on my other computer. I always get a box that says "click here to dowload plugin", but when I click there, it can't find a proper plugin. I DL'd the DivX codecs which seem to solve some video playback problems on my other comp, but can't find any oher plugins that will help.

scroll down and download some plugins

FireFox Central

[Daliman]

Already been there and DL'ed everything that looked appropriate.