Ah, I imagine that the left shoulder doesn't physically move further from the ball, I think that's impossible. I interpreted it as instead of moving the shoulder down and out(clubhead more down the line), you're moving the shoulder down and the club more inside the ball.
Depending on how far you are from the "center of the matrix" you need different things. This particular point seems to address the issue of being too steep in the backswing. NSA feels like you keep the shoulders level, no down all in. SD feels like a little shoulder tilt with some in.
