Poking around Myth's bug tracker, found a few useful ones we could merge into ours. Display movie's metadata image as folder icon - http://svn.mythtv.org/trac/ticket/3579 (maybe) Add detection of more containers/extensions by default http://svn.mythtv.org/trac/ticket/5686 (++) I thought there was a 3rd one. Oh well.
Let's talk about these some more on IRC.
Would also love it, if you could add this one too. It's causing me pain because I switched over to Internal player from mplayer. Thanks! http://svn.mythtv.org/trac/changeset/23020
Fixed in 0.23, please use that version.