After watching this video several times I would contend that this would be better referenced as a shark "incident" rather than the media sensationalism of a shark "attack".
Most of what is shown is the shark trying to free itself from entanglement in the surfer's leg
rope. No one was bitten. No boards were bitten. Only the leg
rope suffered damage. The shark was probably curious about the surfer and then frightened by the entanglement in the rope.
If the shark were attacking, a piece of the surfer or his board would be missing like when a shark bit off surfer Bethany Hamilton's left arm several years ago.
Yes, it is a frightening incident to experience. I am happy that the surfers are safe.
Sharks are usually present in even if we do not see them. They are generally curious, relatively cautious and have poor eyesight. Considering how many humans are swimming, surfing,
diving, windsurfing, kite boarding etc in the world's oceans on any given day, true shark attacks are really rare.
Swimming with Sharks
Diving with Sharks
Hand Feeding Bull Sharks