IE10 Update has broken JW Player
I think this is more of a "heads up" than an actual question.
The latest Windows update included KB2817183, a cumulative security update for IE10. It has broken JW Player. Your own demo page (http://www.longtailvideo.com/jw-player/) doesn't work properly any longer. The error message is "Error loading media / File could not be played."
Uninstalling that Windows update appears to cure all of the problems.