I've never used Automatix, but I think that is what you want. It will allow you to install everything that you need to get all the video that you want working in Firefox. In particular, it installs Mplayer, and the Mplayer plug-in.
If you really do want to pay for something though, what you were talking about is called CrossOver Office
. It has the ability to run many Windows programs including Windows Media Player. But IMHO, it's a waste of money if all you're using it for is a browser plugin.