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.

>>29
Do you even look at a programme source code or contribute to it in anyway? Like 90% of user bases don't. If you don't, how does it make a difference between using a close-source programme or a open-source one, DESPITE the close-source programme being far superior in all aspects?