The technique you described is a still valid training method to teach the dog to pay attention to YOU when healing. If he pays attention and stops when you do, he won't get jerked. It generally works well and does not require many tries before the dog learns to watch and pay attention to his handler.
HOWEVER: This guy is obviously a heavy handed individual who does not understand excess in his actions and is clueless to what he is doing. Sad for the dog. Hopefully the dog will learn quickly and not be exposed to more of this. I have a feeling this guy will be mistreating his dog in other ways, too.