Welcome Ben
This might be part of the problem with the stall.
The squat looks pretty good, but I'd like to see you stay tighter into the bottom. You're letting yourself "drop in", and to do that something has to be loose for a moment. When things get loose, you get off balance.
See if you can stay tighter into the hole. Reach back with your ass and enjoy the stretch of the hamstrings.
Then read this, if you haven't already.