Weight has **** all to do with it,
Oh but it does, you see to change direction (up and down) over the bumps takes a LOT more energy and impact when you're twice the weight of someone else. I notice a difference in smooth-ness of my own riding +- 2 stone, despite my skillz not having changed much in that time.
But ultimately he is a nice clean rider, I love watching riding like that. And the music seems fine to me.
Without having invested any time in envelope calcs, I'd guestimate that a light person is better on a hardtail (lighter to bounce over stuff and flick about over good lines) and a heavy person is better on a full sus (able to utilise the long travel and momentum to "make" lines, with tougher kit that withstands the impacts)