What he is saying appears to be correct but I'm not sure how that helps on your back swing.
Best not to think too much about how your arms get to the top of the swing, plenty of players all have different actions but probably all have a similar impact position which is what counts IMO.
I just turn and lift my arms as he does in this video. When I started golf I had some lessons and we started on my backswing. If only I was shown this in my first lesson, it would helped me no end.