For those of you who may be having trouble playing the speedrun demos for Unreal released 
earlier today by Mr Shambler, the man who wrote Unreal's demo recording code, Epic Games 
programmer Jack "mek" Porter, sent along some advice:

It seems that Mr Shamber's demos were recored with either the latest client version (224v) 
or the latest server version (225f), if you are running anything other than these then you 
may expereience problems and should either upgrade or downgrade (in the case of those 
testing newer versions) to these builds for demo playback to function with Mr Shambler's 
excellent works.

A good way to do this, especially if you're only doing it for the purpose of being able to 
view the demos is to rename your current \Unreal\System folder to something else, then copy 
the \System\ folder on your Unreal CD over to the place your current one used to be and then
patch Unreal. This way you can switch back to your current version whenever you like by 
simply deleting the new one and renaming your old one back to \System\.

You can grab either the 224v patch or the 225f patch from PlanetUnreal at their respective 
download locations.