It's a short video of Willie Mosconi and Jimmy Caras, both world champs in advanced years, playing an exhibition. Mosconi still had a game face that would cause Attila the Hun to miss a pace.
Here's a little of Ralph Greenleaf, generally thought to be the second greatest player of all time. Apparently, he was a drug addict and alcoholic, but was a great player and quite showman. He was dead by the time he was 50.
The Outside Lands connection is that Mosconi played exhibitions at L&L Castle Lanes on Geneva Ave.