C:\Program Files\Activision\Call of Duty 4\main\Demos

Make a demos folder if there isn't already one there. The problem at the moment is that there's a lot of different server settings and mods being used. So the best thing to do is to just copy/paste a demo into the main demo folder (one above), and both pam/modwarfare demo folders as well.

When you're in game, type /demo demoname and it should start.

If it doesn't work, then switch mod, and try again. It's only a temporary niggle at the moment so I wouldn't worry too much. Feel free to reply if you're still having trouble.

Alright, thank you. I somehow managed it. Could you explain, though, what the difference between the Mod 'ModWarfare' and the 'normal' game is?

Limitations on what you can use while in and on public/private servers. Like which weapons, attachments, perks can be used and what things are turned by default, like the helicopters and airstrikes. Most competitive players use the PAM mod now though, just ifferent settings basically.