Taken from a video off my youtube -
http://www.youtube.com/watch?v=em3sMHhoT28
Im uploading a half speed one now too, the mods will be gone by tomorrow most likely according to mapMonkeys
"A guy called Cheater from mapMonkeys.com created a few mods and implimented them on to the Xbox Live severs of Call of Duty 4. These mods include increase/decrease the speed, infinite grenade, long-distance knifes. The mod is spread when a user comes into a lobby where the host has the mod presumably the host recieved it off someone else like a virus sort of thing. You are infected when you are in a lobby with the host who has the mod, if you leave and go into a match where your the host the mod will be enabled. If your not the host it goes away, you can also turn off your xbox to get rid of this. I will be uploading 3 videos, 2 increased speed and 1 decreased.
This is a private game.
Apparently the long distance knife mod and the speed mod damages your 360 and could give your red rings as a few people have learned the hard way. "