From another Pffffftttt shark expert...
Sharks eat approx every three days naturally, compared to a mammal their survival metabolic requirements are way lower, although some can metabolically produce heat they are cold blooded (physically and IMO literally!!)
Watching that video put shivers down my spine too..
It will likely double the spook factor I get from my kite shadow on the bottom when in shallow-ish water

It neatly sums up why I can't paddle-in surf - way prefer to be able to move along with kite - in the years of Kiting and surf-life saving never seen a shark - just knew they were there - just like those surfers.
Wonder what a drone like that could do by way of warning?? Loud speaker playing Jaws movie theme

??
New-ish legislation makes flying drones and any other R/C stuff a real hurdle run...
Cheers
AP