I don’t know what the heck is going on over there but the embedded videos now work in IE and Firefox. You’ll need to clear your cache and delete all offline content to ensure you have the most recent version of the embedded player on the page.
Safari is still a bit of an issue as the video files continue to show up as “forbidden”. In my experience, Safari has some real problems with getting new versions of cached files to display. Especially in situations like this when a file calls multiple hidden files from another server. This may or may not be the case here but it’s hard to tell without some kind of feedback from X-Tube.
Until this is corrected, I suggest Mac users use Firefox as your browser of choice… Turns out it’s a pretty great browser anyway!