Kapteeni was right. download Hypercam 2
http://www.hyperionics.com/hc/downloads.asp, which should hopefully sort the sound problem, and set the resolution to 640 x 480 on the panel that pops up before recording. it should be on the first tab called 'Screen Area'. width: 640 height: 480
it should record the game fine then, but it'll only record the top corner of your desktop. then again if you're recording the game, you don't need to see your desktop, anyway. if you're still having a problem with the sound, change the settings on the 'Sound' tab on the panel. and if no sound is coming through at all, you may not have a built-in microphone or need to install a new mic. i think.
as far as i know, that's all legal and safe, because i just did it and i'm the epitome of legal and safe dont you know.