I just saw that video as well. I agree - this needs further clarification. I understand it as follows: He sets up a channel next to the Master and routes all the audio into that and then routes that combined audio out for 'bouncing' externally. How is he bouncing it externally? Also, what happens at that point, because from what I've understood he then sends that bounced audio back into the DAW's master for 'recording'. It doesn't really make sense to me.