ZD Soft Game Recorder
Full user review
"It does what it says it does, but it's nothing amazing."
It's a very small file, so it took me less than a minute to download (with cable), and it installed just as quickly. In fact, I had it running within a few minutes of finding this page. It's also relatively easy to use... you just need to set up a few options (such as: where the video will be saved, the resolution of the video, and the hotkey that starts/stops recording). Then you simply press the hotkey in-game to start recording, and it saves the file automatically when the recording stops. The video quality is also decent (or at least as good as can be expected from a free program), and you can choose between different file types (AVI, WMA).
Unfortunately, the program can only record 60-second videos. However, this seems to be the norm for free game recorders, so you might not find anything better. A small watermark will also be placed in the top-left corner of the video, but it's not very intrusive and won't get in the way of anything. There are also some other problems that I experienced which might not affect all games or computers. For example, when recording in F.E.A.R., the program only recorded at the game's default brightness (which is actually very dark) even though I had the brightness cranked up during recording. In other words, what you see might not be exactly what you get. Also, for some reason I was unable to play the files in Windows Media Player (there was audio but no video). Fortunately, the files played properly in Winamp, so this was not a major problem.