It's de facto a rule already. We generally consider posting just a link or just a video with no explanation to be low-content posting, with the one exception being the Flat Earth Media board.
In this specific case, it sounds to me like Thork has done the right thing by pointing out that Tumeni's mode of argumentation was unreasonable. Personally I see no reason to action it any further, although I'm completely happy to reconsider if you think I'm missing something.