Lack of acceleration will be because of the bigger turbos so more lag (interestingly if you read recent drives that people have done with the standard P1, they've gone from "electric motors mean no lag at all" to "well, there still is a bit of lag there" so I suspect initial thoughts were clouded by excitement), although it's all going to be relative.
I think he was fiddling with brake bias or wing adjustment or cooling or simply holding something on that was about to fall off rather than grabbing the downshift paddle. Bearing in mind it's one big piece of metal, so you can achieve the same result by pushing the up paddle away from you should you wish. Interestingly the 720 has known to change gear back to the one you were in if you flick the paddle too quickly