So he's scared because they're pointing a gun at his head right from the off. He's black, he probably knows people who've been shot. They immediately started to cuff him, he wasn't doing anything to be cuffed. He was a little skitish, but not acting, violent, or attempting to flee.
The woman basically confirms he's been shot before, and is scared of police. There was no attempt from the cops to talk to him, and identify the facts, they immediately started to arrest him. I doubt that would have happened if this was some white guy sat in his car.
"I'm claustraphobic" - he's having a panic attack, drug induced or not. Claiming I can't breath in a panic attack while being manhandled by a couple of cops, is very different to claiming I can't breath because someone is kneeling on his neck. That's pretty obvious to anyone with half a brain cell. Once arrested an officer is responsible for the safety of that person, kneeling on the neck of someone isn't looking after their safety.
Neither of us know if he had enough drugs to OD, he certainly didn't look like he was minutes from ODing in that video.