I watched the first five minutes, and he wasn't throwing "lead" anythings. Just about everything he was doing was in reaction to an opponent's jab, and based on the assumption that he was safely outside that jab and therefore out of punching range. Got help him if he doesn't end up there, because he winds up and telegraphs everything he throws and leaves himself wide open with his chin in the air.
Good Heavens, there he was throwing a corkscrew jab, too. I guess the point is to punch over the left shoulder of an opponent, though there really is no telling what goes on in the mind of a southpaw.