My boss says that there's an open source screen capture program that "hackers use to show off in a 'how fast can you hack <x>' contests." He says it's for Windows. I've tried searching Sourceforge but haven't found anything that really fits the bill. Does anyone know what he's talking about? I think we're going to be using it to make help movies on our simulation.

I don't know about free, but FRAPS will record about anything.

Fraps is a good program that I've used before. You can download the last free version that was published here

Its capture size is limited to 640x480, but theres no time limit or watermark if you dont feel like paying.

IrFanView can take screenshots. It also opens just about every image file type on the planet and it's free.