I don't think you can look at the video and claim he is bad at video games. He is bad at platformers, yes, but video games are so broad and so varied that being bad at one genre doesn't impact your skill in another.

Seems to me like you're just discussing this point not because you believe it, but because you want the academic exercise.

That's the problem with responses to these types of events. People at r/games put on their academic pants and start talking about "but what is a game? What does it mean to be good at a game? If a person is bad at one game, it doesn't mean they are bad at all games. But can there be a skill that is universal among gamers? And if someone is bad at a game, does that make their review count for less? What is the minimum skill to review a game?" etc.

Asking all of these questions as if we need to nail every criteria for a review down as if we're writing a scientific paper here, or making every excuse possible (ie "all you saw was one game, so maybe he's just bad at that one!") etc.

Really, we need to put all this posturing aside. Yes, it's so fun to engage in the debate of "but what should our expectations of game journalists really be, given that we have defined our terms so poorly, alas" but really: some game journos are depressingly bad at games, and therefore cannot give good impressions of games.