Can't find a way to justify the beating in the op's video.
Don't know what was going on in the Walmart brawl, or what laws the family was breaking, but if they were committing crimes, they're lucky they're all not dead. I feel I would have resorted to deadly force earlier than the cops did.
As for the Uber driver scenario, I don't think the policeman should be fired but he does need a suspension and schooling on how to react in such situations.. he was out of line.