As someone who is around a killer whale and sharks every day, I'll chime in a bit:
It was a pod of killer whales, and a young white. Not too shocking.
Though, that website's tonic immobility description is WAY off from the facts. TI doesn't prevent a shark from beathing at all. It slows them down, not like they describe as 'waiting until it can't breathe and dies'. I use TI alot when working on sharks and rays doing medically related work. It's a great safe way to slow them down without hurting them at all. TI is also not complete immobilization. They will still struggle and fight if they don't want to go down, and it's not something all species give into - it only works on some of them. I would also like to know more about the white shark. Was it healthy to start with? Was it as young as it looked?
For the stingray footage...amazing indeed. However, the teeth of the whale are what's stopping the ray, not being flipped over. 44 conical shaped teeth punching through the head and main body cavity of the ray will render it helpless as it's flipped over.