<<Note: This is a discussion for lessons-learned sake, not conjecture into probable cause.>>
As an aviation safety investigator, this video leaves me asking plenty of questions that won't get answered here. Are those the right flaps for this phase of flight (takeoff or go-around)? Is the engine producing full power if it was commanded? Why was he turning rather than proceed straight ahead if the pilot was approaching a stall? And did he know he was nearing a stall?
I agree completely: An AOA system is hugely valuable for avoiding events like this, but please get smart understanding what the instrument is actually telling you and what to do about it. Stall AOA can differ for different aircraft configs (ie, flaps up or down) and bank angles. Fly safe!