He said he has been "working for amazon" for a while. But dunno if he works for Amazon directly, A Amazon Delievery Partner or Amazon Flex. I'm sure he has said its only part time Atleast here in the UK you use your own vehicle when using Amazon Flex.
So he probably didn't sign up just to make this video.
Clueless about the Amazon Flex part (never heard of it, and I'm not in North America).