I would tell you what it is defending, but that would be spoilers.
But you should at least get to around 23 minutes in to find out why he says: "lion, lion, Lion, LION --- oh, I better get going"
I lost attention-focus about two thirds of the way through the talk, after he said "I wish there were languages that defaulted to persistent data structures". Has such an FP nut not even heard of sml, ocaml, haskell, etc.? Or is he just slyly setting up his audience for a surprise later?