Looks to be a Malinois, not a GSD.
The problem with training dogs this way, is you can BET that the dog will challenge you back for that alpha role. With apprehension dogs, I wouldn't want my dog to challenge me!!! I've seen a lot of police dogs trained in a more 'traditional' manner just fine. Never seen this first hand though.
This is not cruelty, but I sure wouldn't train my dogs this way!!