OK, here is a new vid from Sheffield...
Back flicks towards goal, and he tries to shoot into the (narrow) space between the player and the wall. Shot blocked by the shoulder of the defender.
Is this then dangerous play, or an illegal stop?
YouTube - Underwater hockey: blocking shot or dangerous play?
(sorry, it is a link, since this one just doesn't seem to want to embed properly...)
My opinion: easy one; penalty goal, kick the defender out for the game, credit the goal to the Dutch #2 (actually, why not give him a couple while we are at it), and case closed.