He asks did you have back pain when you came up? She answers No. He then reasks do you have pain now. When you are sitting in the front of a room as a demo subject the presenter has an undue amount of influence by virtue of his positional power. The implication of this type of questioning is to hypnotically suggest that she should have some pain (so that he can do this demo). Then he reinvokes the pain by asking her to go back and remember when it was "really strong" She says Yes. He then reinforces this by asking ostensibly the audience, "Do you believe her? And then makes the metacomment, " Oh Yeah" while nodding in affirmation. This is all a way of rehearsing the client through the pain, which moments ago she said "No, it is so much better now." But he didn't leave that. Instead he brought it back so that he could get rid of it again.
You can easily deal with problems without going to their origination point if you know how to do that. It is a myth that problems can only be solved by accessing the memory where they began.
I agree that many people do dissociate and try to bury their suffering and pain as a coping mechanism. And that this doesn't usually work very well, the pain keeps returning until it is reintegrated one way or another. But the idea that the fact that she remembers somehow means that it wasn't better is not right. Healing and reintegration don't create amnesia. Especially if you do as he has done with this client and re-access the old memories. This is tantamount to reinstalling the painful experience. Very easy to do if you don't know what you are doing. I see therapists make this mistake all the time. But I am pretty sure that he knows what he was doing and did it intentionally for the sake of the demo.
This is why I don't support his ethics. Good that you do though.