I have seen that video. And he does a great job explaining things. But all the things I've read and watched have left me unsatisfied in answering Sam's question. And I think I understand what he's asking, because that's how I would phrase it.
Since there isn't an object at L2, what is allowing Webb to orbit it? Scott Manley simply says that "there is a force pulling it back", but doesn't explain anything further.
I think the answer is that Earth, and maybe the Sun too, is pulling on Webb and making L2 a preferable position than "some distance away from L2". That is…If Webb wasn't in a halo orbit around L2…If it was just sitting at L2 and you pushed it away from L2 a little bit, the gravity of Earth (and Sun?) would pull it back to L2. The situation just seems weird because Webb isn't orbiting a mass.
But also, "love". That's the "L" in "L2", afterall.