I am not so sure I like the way that wrist lock was done. He left way too many openings, and waited way too long before getting any effect out of the bad guy.
Watch and you will see 3 distinct movements:
1. he grabs the bad guys hand, taking it down off the girls hair
2. he raises the bad guys hand up, so that the forearm is vertical
3. he twists the wrist and takes the guy down
During steps one and two... the bad guy is not effected at all, other than his hand is down and then up. Notice his posture and balance does not change at all during steps one and two. Only during step 3 does the bad guy's body get effected but the lock. What this means is he did not connect to the bad guys center for two counts there. During those first two counts, since the bad guy was completely unaffected by the hand hold... he could have punched the guy, he could have pulled a knife and stabbed the guy (people that know knives can produce them scary fast), he could have shifted his feet and shot for a double leg... he could have done anything.... but he just stood there and allowed the lock to happen.
There was also a separation of the movements, like an extra pause between each step: down - pause - up - pause - twist.... this just gives extra time for the bad guy to respond. The escape from that lock is to face the guy grabbing your wrist, and extend your hand out, rotating the palm down.... he had two counts and two pauses to make a quarter turn towards the guy while extending his hand, breaking the grip and setting up the double leg....
What would have made things better.....
1. Remove the pauses.... from initial grab to take down, should be one continuous movement, not three movements separated by pauses.
2. Remove slack from the system... the initial grab going down, should have blended into and movement away from the bad guy... this connect the elbow to the shoulder, to the spine... breaking the bad guys posture and taking his balance.... while removing the slack
3. Make a smaller circle for the take down part. When you take the hand down and away, keep it at that same level as you rotate your body through the wrist.... picking it up into the air gives back all the slack you took when taking the hand down and away
By applying these corrections, he connect to the bad guys center, takes the slack out to make the lock tighter, destroys the bad guys posture, takes his balance and makes it very hard for the left hand to reach him and makes it very hard for the bad guy to turn into the lock. Additionally, these details allow you to have more control... going faster or slower, harder or softer as the situation dictates.
I know, you are reading this saying "but it worked and put the bad guy down." He was not really a bad guy.... he was an actor, who was not actually being violent with anyone and would not respond violently to the "helper." Had this been a case of actual real violence, instead of an actor playing a scene, I have a feeling this would have turned out differently. If he was grabbing her hair in real violence, I doubt it comes off that easily, when he lifts it up in step 2, he gets punched in the mouth and the lock is gone.
I give him props for doing something and not just walking by.... but the execution of the lock and take down, was not good for me. Try that exact technique, as he did it on someone not wanting it to happen and things go very differently....