I have no clue how it went down, I'm just a rando HN commenter, but don't ascribe to careless human moderation that which can be adequately explained by automated moderation.
There's definitely a sizable crowd that prefers HN to be more about hacking and less about politics, let alone divisive discussions about intelligence services, the person of Glenn Greenwald and so on. Also I wouldn't be surprised if HN has a lower flag->dead threshold for video links.