Mplayer plugin help

I'm not sure what's happeing with my mplayer plugin in Firefox. It seems to be working because I can watch wmv9 files from my desktop within Firefox as well as embedded quicktime movie trailers from apple's site. But embedded files like the previews on Netflix, or videos on CNN.com just show an empty gray box where the video should be.

These were working at one point I think, but I was tinkering and deleted the association in Firefox settings. The listing in 'about:plugins' are all there for mplayer including ones for wmv, avi, mov, mpeg, etc. But, like I said, they're not all working.

Any thoughts?

did you get codecs?

Yes. I should have also included that I have all the codecs. As I said, it seems to work, both outside of Firefox (MPlayer the app can play anything), and in some cases, via the plugin. I'm not sure how this is relevant, but it seems that the times when the plugin does work, that the video being played is not embedded in a web page, but being played directly (ie. if I open a wmv file stored on my system or a web link refers directly to the wmv file). Again though, movie trailers on quicktime.com are embedded and they play properly. :-?

Anyone know what format Netflix and CNN use?