Let's just recap:
Antifa guy with a baton tries to attack some dude
Somehow doesn't avoid a mile wide right hook and is knocked out
The guy who knocked him out picks up his baton and walks away
How do you fuck up that badly?
Antifa guy has real bad foot work, as
@Fagnasty said. Antifa guy swings with his baton from way too far away, and makes the big mistake of swinging from his back foot and then stepping into the swing (complete with his foot leaving the ground), but then also swinging with real short distance (despite being far away) and still doing a full range of motion. That puts him off balance (from his foot leaving the ground) and his hand way down (from over swinging the baton with his haymaker of failure). This combination of being off balance and his hands being down is a bad thing. He's lucky he didn't get KOed with the first swing...
Then, he steps backwards and throws it again with a way too long motion, this time keeping his feet on the ground but still very off balance. Being off balance with his hands down leads to an easy shot to the head by the other guy, where he pulls back his arm, but then ends up throwing a hook which catches the antifa tard (who is still off balance) in the jaw. Antifa guy had his hands down and made zero attempt at defense.
The other guy wasn't exactly Mike Tyson, either, but at least he kept his hands up when defending and had good distance. Also had a real strong hook, although he should've gotten back into stance instead of hooking through at the end (after throwing a strike, get back into stance immediately). Antifa guy did literally the exact opposite of what you should do at every part in the exchange.
tl;dr - keep your hands up when you're fighting. there's a reason boxers use that stance