SoundFlower can let us play the system's audio to the SoundFlower 2 channel and record with this SoundFlower 2 channel, so QuickTime on Mac OS X Lion and record exactly what the system is playing for a game play.
And it works for 16 channels as well.
But is it true that while we can record the sound, we can't hear it? So if we are playing a game and we are recording the video/sound, then we can't hear it. I just wanted to set it up to record the ending credit and the song, but if it needs to be played without sound, then that's somewhat a problem too.