You don’t have a monopoly on reasonableness. Twelve jurors, not Redditors, agreed that the YouTuber was behaving aggressively, and violence is a common response to aggression.
And the YouTuber’s entire shtick is to make people think they might be in danger, by not letting them back away. Because that’s how fights commonly start. If he did the same routine ten feet away from his victims, the whole shtick would fail.