Frocto uses Camtasia, which I experimented with and quickly despised when it fucked up my videos. It has a nice UI though. If you can get it to work for you, more power to you. However, it is not free (30 day trial).
I use FRAPS, recording at 50 fps at 1440 x 900 with the audio input set to Microphone. (For my Curse Ep 1 video, I actually didn't do this, I had headphones on and had the microphone recording in GoldWave, and for some reason FRAPS did not record any game sounds like I thought it would.) I turn the speakers up all the way because the microphone picks my voice up far better than it picks up what comes out of the speakers. And I don't have any audio sync problems whatsoever this way.
Then (at least, for the Portal video) I open up the AVI in VirtualDub if necessary, cut it up, for whatever reason it doesn't want to encode to DivX so I just make it a Microsoft Video 1 AVI at 90 percent quality and "process every other frame" (which converts the video to 25 fps) and then I open up TMPGEnc and make the huge, gross, bloated AVI into a tidy little MPG which looks just about the same.
For some reason, MPGs need to have their dimensions in multiples of 8, so I have to change the resolution from 1440 x 900 to 1440 x 896. Go figure.
I assume that I can use VirtualDub to string several AVIs together (FRAPS cuts them up automatically as soon as they hit a certain length) but I have not yet tried it. When I tried to do it with Camtasia, terrible things happened.