My guess Aaron Pryor hittin the bag in his twilight years .... no clue tho kinda hard to see... RIP champ
Well, I've seen color home movies from Floyd Patterson's gym that were filmed in the early 70s. Those films kind of look like that film does. So, assuming it is Floyd Patterson's gym, I would say that kind of looks like Raymond Patterson, Floyd's brother, who boxed until the early 70s. The face looks similar. And Raymond got thicker around the middle as he got older. So, wild guess, Raymond Patterson in the early 70s. (Doesn't look like Jimmy Young at all, to me.)
He has that Bennie Briscoe-like chug about him. Don't know if that was something taught in the Philly gyms. The first guy I thought of, however, was west coast light heavy Eddie Bossman Jones. But I've seen so little on him I can't be certain.