What is being used in the video is pork jowl, known as guanciale in Italian (basically cured pork cheek) . It has a high fat content, even compared to pork belly. Fat is flavor, so no convincing from butchers is required. Also, it's a cheap cut, so if they want to make money off their customers, they'll want to also sell things like Secreto ibérico, or better yet, jamón ibérico de bellota.