poor quality for the win!
this is how the pros do it:
while in game type /record in the console , this will same a game demo file (playable only in cod4) but it will not hinder your performance in anyway. to play back the demo type /demo demo#### numbers start at 0000 and go up from there. You can also use cybopat's player, you just open the file and it automatically launches cod4 and starts playing it. Cybopat's also lets you mess with stuff like speed and camera angle. Download it here: http://www.cybopat.net/vb_cod4player_eng.php . When you want to record a real video file just play back the demo and use something like gamecam (see above), but i prefer Fraps. Then just use windows movie maker or something similar to edit into a kick ass kill-fest.