I wish I had enough control of my back muscles to try it both ways, and be aware of the difference, so I could find out which worked better for me. So far, my goal has been to get into the posture he says is out of balance, since the feeling of my shoulder blade moving in toward my spine is a signal to me that I'm using my back muscles. I'm not sure how I would get into the posture he calls balanced without using my string arm muscles more than I should, which I'm sure is not his intention.
In KiSik Lee's and Tyler Benner's book, Total Archery, Inside the Archer, there are several photographs intended to illustrate correct posture of the back at full draw, all of which would seem to be out of balance posture in the video, in that the drawing side scapula is pressing in toward the spine, creating a wavy vertical line where the scapula is compressed toward the spine . I'm sure this would all be much easier if you had someone there showing you as opposed to trying to figure it out from pictures and videos.