The uploader of this video claims this is based on actual events, though I don't know if I can see Doug going so far as to actually beat somebody up at a con.
Having said that, have any of you seen that clip where he's speaking at a panel and he's talking about an incident at another con where he and Rob were visited by some guy who just stood there and kept asking him random questions, and apparently gave off a stalkerish vibe to them because he wouldn't leave, while also saying he felt like the guy wasn't all there? Apparently that same guy recently spoke out about the incident and shared his side of the story, saying he was only fourteen at the time, on the spectrum, and incredibly nervous about meeting one of his biggest heroes like that, so of course the encounter wasn't entirely smooth, but he really didn't like how Doug basically made him out to sound like he was a creepy stalker or something.