I clearly saw some aggression from the dog in the video. Which is understandable since his owner was being arrested – the dog’s natural inclination is to attack the people that he sees arresting his owner.
This is also a dog breed known for aggression, we aren’t talking about a tiny toy poodle here but a large pit bull. Per the ASPCA:
Pit bulls have been bred to behave differently during a fight. They may not give warning before becoming aggressive, and they’re less likely to back down when clashing with an opponent. When provoked, they may become aggressive more readily than another breed might. Sometimes they don’t inhibit their bites, so they may cause injury more often than other dogs.
It’s an unfortunate situation all around, but when put in a position where I could be mauled and disfigured for life by a large, aggressive dog who perceives his owner to be under attack – I’d also choose to put the dog down.