What less cruel techniques are there? In Europe cattle are killed with a bolt through the brain ... quick and painless. Apart from the fact that quite often the animal doesn't die from the bolt and is still conscious when its put up and disembowled.
I used to work as a butcher and was involved in most stages of meat preparation - the most humane method is Halal, where the animal bleeds to death, basically it feels the cut but then falls asleep. I don't think you can easily do that with a Dolphin though ...
The video shows unacceptable treatment of animals, but there's no perfect way to kill. Where's the videos of hunters winging animals and condemning them to a slow death? That happens in almost all countries.
As for saying 'Dolphins are different', why? If its ok to eat cats, dogs, horses etc, why not Dolphins?