A lot of the objections to my, and Mikey's, points might hold a lot more weight if there hadn't also been a coroner's ruling of homicide. In that respect it seems incredible that not even any charges have been brought. And, heck, the coroner will have had access to most, if not all, of the evidence, so it's not like his opinion will have been entirely ill-informed.
The video seems to imply that the resist of arrest lasted barely a few seconds before one officer went for the neck. I find it equally hard to believe that other, less potentially life-threatening, methods of restraint weren't available. They certainly can't have been seriously considered. The guy was already outnumbered. That should have been enough in itself to restrain him without leading to his death.
It's one of several incidents that smack of an attitude police in the US take where they rapidly jump to the final sanction before going through any of the others. A 12-year-old boy was shot dead within two seconds. That strikes me as incredibly quick, especially when it's clear that the officer involved erroneously reached the conclusion that he was "maybe 20". It's an attitude that should be far more troubling than it seems to be. Perhaps because we're mostly based in the UK, so it's "over there", and less of a threat.