I have the native mPlayer for Panther, version 2.0 b8. It wasn't finding the codecs folder because I lowercased the name of the folder, codecs instead of Codecs. :o It was in the correct place, hd>Library. Now it plays things it wouldn't before.
What else can I put in the codecs folder, like for real media or Flash? I don't care if it's "legal" or not. It would be nice to be able to use mPlayer to recode audio and video to more common file types.