I think the new youtube design that's still being rolled out looks better than cosmic panda, and this extension works with it.

If you want to try it, set the following cookie (and disable cosmic panda obviously):

    document.cookie="VISITOR_INFO1_LIVE=ST1Ti53r4fU";

(From: http://www.redmondpie.com/heres-how-to-enable-the-new-youtub...)