When you get to the end of your turning limit, you put the power steering pump in full demand as it thinks you are trying to turn thru the steering stop. This demand tells your pump, give me everything you’ve got and typically drives pressure over the relief valve in the steering gear.
The noise you are hearing is strange. Typically this demand can make your belt slip/squeal, and that may be what’s happening but you may also just be taxing some other component (tensioner, pulley, etc), resulting in the noises you are hearing. My bet is the tensioner.
Try this: put a big chalk mark on the smooth side of your belt, have a buddy, friend, spouse, or complete stranger perform the turn left routine in your video while you are watching the white chalk mark. If your highly calibrated eyes (I wear glasses) can pick out a slowing in the chalk mark speed, you may figure out that the belt is slipping.
Good luck and report back your findings.