I've participated in those demo with several top shihan. I'm sorry - there is not a human being alive who could do that. One appreciates that one has to cut in such a way that contact is not made.
Or as Kuroiwa sensei said to me, "Of course, you couldn't hit Osensei." I asked, "You mean, you couldn't hit him?" He replied, "That's what I said. No student of Osensei could hit Osensei."
Well I would love to hear your take on "the jo trick"....