Huh. Okay, that is pretty bad
Thank you for recording the video, it clarifies things immensely. It is also odd that the browser never loads the pictures.
I do not know what to say other than it works in FF19, all the webkits (from android to safari), IE10 and Chrome. I'd really need to sit down with Firebug on a computer with the problem to get to the bottom of it. To that end, it looks like you are on Windows. It should not matter (but just in case) which version of windows? And 32 bit or 64 bit? And we are taking about the latest FF beta binaries, 21.0b3?
Taking a single random shot into the dark, I'm guessing the problem might be related to some junk that was added for IE8 compatibility. It's been cut out. Does it act any better after a page reload?