Put yourself in the shooter's shoes for second. You are there to back up the less than lethal guys who are going to make the arrest. The guy is shouting threats to kill and is clearly an emotionally disturbed person who is a danger to others. Flash bang goes off. The dog goes toward the guy. The canine handler moves forward and crouches down in front of the guy who is holding a knife and is known to assault officers. And the guy with the knife moves. I don't know if it was to get on the ground, or flee but he did lift the knife at the dog and lifted it again and took a step forward before his body started to turn during/after the first shot. He turned during/ after the first shot. look at it again. The knife was moving forward. Listen for the first shot. My sound driver on my computer has a slight delay but listen for the first shot. pause it and look where everyone is at the 54-55 second mark. Look at what he does at the 52-53 mark. And know that its not usually an instant stop if you do shoot.
The canine officer moved in too fast. Maybe it was to stop the dog from mauling the man. Or to protect the dog. Either way, he should not have gotten that close until the guy dropped the knife.
Either way, good shoot or not. It was not just to shoot a guy over a ten dollar ticket as the media claims.