I used "Software Capture". However, here's the thing... most likely, Geneforge runs at a resolution much smaller than your desktop. So what you have to do is change the size of the screen the recorder is recording at. Open up "Settings", click on "Video", and customize the Resolution it is recorded at to the precise resolution of the game you're recording (You can find this out on the Games page here, although I think the first game is 800 x 600).
And now, the next episode with... not that much here to be honest.