I do these videos unscripted, so after a few takes, I just go with what I got. Basically, the message here is to use the strength and flexibility you have in your trunk muscles and connective tissues to guide your spine into the appropriate amount of rotation. The minute you leverage your twist to go deeper, in any twist variation, by cranking your arm against your knee, you have moved beyond the boundaries of your own strength and flexibility and taken your spine into an inappropriate rotation. A good rule of thumb - if you are not strong enough to get there on your own, you shouldn't be there. Don't cheat your twist.