"I cut throttle, slowly pull up elevator to get the nose up, add a little throttle to keep it from stalling. "

I havent watched the vid but right there is your problem. A harrier should be flown with a stalled wing. Try bringing it into a wall to almost a hover and harrier out of that so you are already past the stall point when you try and start the harrier. Remember when your in a harrier your not actualy flying on the wing but using raw thrust to pull it around and to keep it from falling out of the sky. Your wing rock is prolly comming from flying on the wing but right at the edge of stalling the wing. Once you are post stall it should be more stable.