This looks somewhat similar – http://watchitoo.com – where you can have multi-user video or text chat about YouTube videos. I haven’t played around with it much yet, but it looks kind of cool. Could make the Presenter pre-lectures that instructors are doing interactive. On the Public Shows tab there is a tutorial video.
Good use of VoiceThread. (If there is no sound and no movement, You have to press the arrow to the right to advance)