@dwynne:we run that site as well, so I can tell you that it isn't the same player... not in the way that matters here. Our player is using a new SL4 feature, full-screen pinning, that the MIX site is not.

There is a video on this topic here: http://www.silverlight.net/learn/videos/all/fullscreen-window-pinning/ *and* that player uses the full screen pinning feature, so perhaps you could try to run it in full screen?