That was last year, I've seen it before. I also saw the same collision filmed from a third vessel. It's plainly obvious that the smaller craft (was it a catamaran or a trimaran?) accelerated directly into the path of the Japanese whaling ship. IMHO there's no doubt they did it with the express intention of causing a collision. I'm not sure they quite recognized that the result would be the sinking of their "ship," though.
I've also seen other videos of the greenies deliberately ramming the Japanese mother ship with the Steve Irwin -- which is a real, honest-to-Blackbeard, steel-hulled, ocean-going ship. They're lunatics. I don't especially support or even sympathize with Japanese whaling. I think it's obvious that they are gaming the treaty. But the southern ocean is a dangerous place, and any ship that attacks another ship fully deserves to get a few rounds out of an 8" gun.