Try Worms Armageddon
You can name teams of worms and set them as CPU teams instead of human teams.
You can also name each worm on a team.
Just load up as many teams as you need, press play, and watch the AI battle it out! I would suggest to give each team the same special weapon to avoid any balance issues.
The game also records a demo of every game played that can be played back in the game client afterwards, so you wouldn't even need fraps. Although you could still fraps (or dxtory with x264vfw for a much lower filesize
) it if you wanted, as it's been updated with a DirectX9 renderer in recent years (not bad for a game from 1999).