Alternatively: Get a camera that does sound+video, a power cable for it, and a tripod to put it on. Then proceed to record the PC screen. That's what I came up with, because recording using screen recorder software is too slow with a game running (by its very nature - you don't get hardware acceleration).
But yeah, that does cost money.
For freeware, try CamStudio. It's not trialware, crapware, or crippleware, either!