Nothing. My headset when plugged in doesn't give options like that, and two CamStudio right out tells you "Video and speakers" or "Video and microphone".
If it can record one, why in hell is it so hard to find one (even one to BUY) that can do both?
Did you read the instructions? These steps have nothing to do with whether on not you have a microphone plugged in. They are straight-up OS configuration instructions.
If it can record one, why in hell is it so hard to find one (even one to BUY) that can do both?