Apparently the game will only run at 60hz on UK televisions. Dogzilla at the xbox.com forums found a fix for this.
Also for VGA connection:If your getting the Pal 50 not supported do the following:
1 - Turn off console
2 - There is a switch on the connector of the component cable , switch it to TV
3 - Power on the console and go to System/Display/ PAL Settings,choose PAL 60 and save settings
4 - Power off and flick switch on cable back to HDTV
5 - Power on, you are now displaying in PAL 60 (Providing your TV supports it)
6 - Demo will work now
Source: UK Demo Error SolutionHere is the fix if you using VGA cable.
1. Unplug VGA cable and plug in the component/composite that came with your 360.
2. Plug this in to a TV and make sure the switch is flipped to TV
3. Turn your 360 on.
4. Go to System blade, Display > PAL Settings and set it to PAL-60.
5. Save the settings, Turn your 360 off.
6. Plug your VGA cable back in and play the demo!