I have tried with my server team to troubleshoot this plug in in a MU instance, but it does not work and even breaks the CSS in activated pages. It's sort of looking like a theme incompatability, but I can't find it. Here's a link to the offending page that I'll leave up for a little while:
http://sites.la.utexas.edu/faculty-ipad-initiative/another-test-video/
Any suggestions?
http://wordpress.org/extend/plugins/jw-player-plugin-for-wordpress/