We don't really support Ubuntu, so it's hard to say, but you're not the only linux user (not the only Ubuntu-specific user, either), so maybe someone else has some insight into this?
It fails to work for me in Chrome, Chromium, or FireFox, using Flash 11, on Ubuntu 11.10. I reach the initial loading screen, receive an infinitely looping progress wheel after a bit, and then nothing. It's been doing this for about the same amount of time as the OP has been having problems.
Not to add a "me too", but .... It fails on Gentoo Linux, Flash 11.0.1.152, on both Firefox and Opera.
At the Self-help screen Firefox 7.0.1 stops at "Flash Player: waiting"; on Opera it errors with
Flash Crossdomain: Failed (Timeout)
Game Server (port 443): Failed (Can't connect)
Game Server (port 1443): Failed (Can't connect)