The camera (on the video from ahead) is not sitting still on the ocean, but moving diagonally across the path of the whaler. If there'd be anything in the background you would see it's simply the constant change of perspective giving the illusion of the whaler turning to right.
I know what you are trying to say but you're incorrect. When looking at the video from ahead, you see the whaler make a turn to starboard, then straighten out, then ram, then continue straight.
If this turn was an optical illusion due to the camera moving from left to right (relative to camera), you would not see the whale boat straighten out, you would continue to see the port side of the whale boat.
This, in conjunction with the camera on the whaler, shows an intentional turn to port in order to ram the batboat by the whaler.
One can argue that these batboat guys had it coming, I've got to admit I snickered at the video myself.
But it is intellectually disengenuous to claim it was anything other than an intentional ram only because you empathize with the whalers.