It will work everytime "Warmup" finishes and the game starts proper, so if you have a game and you want to keep the demo of it, then you have to take note of the following:
DATE:
TIME:
MAP NAME:
Then make a post with the details in the demo request area of the Forums.
Done!
One last thing, you can shoot Epic for this next step, but for reasons only know to them, you have to MANUALLY install the following mutator for the demos from our server to work;
http://kismet.kaoshq.com/_kAoS_uT3_Demo ... dverts.rar