One of the most astute points that video made is that when he gets pressed up on, he doesn't have the lower body strength to not get moved around some.
He also doesn't have a mental alert system that when he gets pressed tight on the perimeter that he needs to be even more cautious with his dribble.
He keeps his upright posture and high dribble (which isn't tight to begin with). Weaker ball-handlers, or at least ball-handlers who are dribbling with their weak hand, should instinctively know that they need to crouch more, use their off hand/arm to shield their dribble, and make fewer/quicker/shorter dribbles in that case. Not stiff-backed, high-dribbling, without shielding the defender.
I think Jaylen's #1 problem is his overconfidence. It suits him well in so many other aspects of his game. But in this situation, when it comes to dribbling with his left, it's his achilles heel.
He has an achilles hand if you will.