thats the source package you downloaded.why try and compile from source?search for binaries in your distro's repos.
BTW what distro?
Oh I did not know that the plugin will also be available in repos, I was looking at mozilla addon site & google.
I got that now finally & can play the WMP content now.
But the youtube site still not having the sound, I can see the video, what else do I need to get sound at youtube. My sound cards are working fine nothing is mute