The idea that "It's all a simulation/game/dog's dream" is hardly new, and by its nature its an unfalsifiable claim. Meaning, sure, it could be, but there's no way to know, as any way of checking is also part of the game.
As far as your possessions via ouiji board video, I'll give you this, you at least find high quality shit, not just some complete obviously fake garbage. I'd be interested to read some explanations for what might have happened there.
I'd suggest it could be good ol' mass hysteria, although I find that a pretty weak claim on its on. Especially with the seizures and stuff, obviously anything can be faked.
Another quite realistic possibility is the entire thing is completely staged, the kids are part of the act.
There's also the "chemical leak" explanation, these kids just so happened to be playing with a oiuji board when some chemical vapor made them hallucinate and have seizures.
I have a question for you now. What if I decided to fuck with you? Meaning, lets say after the last time you said "I think maybe corbin is missing because of the missing janitor stuff we talked about". What if I went along with that? Or hell, what if I told you I took a long time to respond to this ouiji board business because I was possessed by a demon after watching the clip? What if I told you I was visited by men in black who told me to shut up about the fucking janitor? Would you believe me?
I mean, from what I've seen, couldn't I get you extremely worked up about this nonsense if I were so inclined? Because although I'm not doing that, you had no way of knowing I wouldn't. Have you had people do that before?