This is a training exercise from the sport of French Ring - where the dog must protect the handler and can only bite once the decoy hits the handler.
Pay special attention to how Hyper heels backwards before the bite in order to watch the decoy - a very fun exercise to train.
It involves so much more than just making a dog aggressive. The dog should be stable and social, highly obedience trained and the methods used should emphasize stability and control. There are many dog trainers out there make sure you are trusting your dog to the right one - your safety and that of others may depend on it.