Any program (Windows Sound Recorder, Sound booth, audacity etc) that records audio can record sound from windows, you just need to know how to set windows up.
You are not really looking for another screen recorder that will work, but rather how to get to record audio.
I use HyperCam and CamStudio, both free, they record video and audio.
I when through this struggle, and tried MANY different screen recorders. None of them will recorded system audio "out of the box."
My answer came from an article like this article (sadly I can not find the original article I learned this from).
It is very easy to do, once you know how, just three steps:
- Right click on the sound icon in the system tray, choose "Recording Devices".
(Here is the hidden part) Right click in a empty part of the list, choose "Show Disabled Devices". Now magically a new device "Stereo Mix" shows up. That is the device that will let programs record sound.
Now in your recording software open up the audio options and set it to use "Stereo Mix".
This is a screen shot from HyperCam, but every software will have similar settings.