They already had the guy restrained. Shouldn't the next move be to check for weapons? That knee to neck move for that long period seemed unnecessary. It would've been a different story if that guy was still walking around, had a knife or a gun, and started rushing towards the cops. In that situation, killing the guy would be legitimate. This one though, isn't, because they already had the guy restrained.

In a lot of videos where I saw some dude was being restrained, the moment they find no weapons on him, they usually remove the pressure on the guy's neck. Sometimes they still keep him down or they put him against a wall. First time I've seen one like this where the cop just continued to put pressure on the guy's neck until he died.