Not OP, but it is possible for something to be both "obscene" and "helpful" (maybe we should say "of value"?) Say... footage of Hiroshima? Or the liberation of concentration camps? I'd say those are examples of things that are both obscene and have value.

So I think you're looking for another property those videos have in common. It might be closely related to obscenity, but I think it must be a bit more nuanced than that. Why are those videos valueless? (I don't know the answer).