Sometimes when I play a good game, I realize I forgot to record it. I'd like to have it automatically start recording the game at the game start, and name it "demo####.dm_69". It would start from demo0000.dm_69 and continue all the way to 9999 before starting over again at 0000. This way, if I forget to record a demo, it's still there, and I can rename it to whatever I want. At the end of a game, it should display "Demo automatically saved as 'demo####.dm_69'."
I got the idea from Starcraft and Warcraft III's reply feature. By default, the replay of the game is automatically recorded. If you don't "save the replay", it is saved anyway, as "lastreplay.rep". If I wanted to save the replay, but forgot, it is still there, and I can simply rename the file to what I want it to be. Of course just naming it "lastdemo.dm_69" would not be a good idea, because it would be immediately overwritten when the next map is loaded. Hence the #'s.