Seemed to be fast enough that there was no obvious danger of stall/spin.
Of course one would have to follow the local low-flying rules, not too close to boats or whatever. (In BC there's a rule against landing within half a mile of a whale, but as soon as you land the whales, being friendly, will swim over to have a look, so there's no rule against taxiing and taking off within half a mile of whales.)
Which just leaves engine failure ... which, assuming the guy was wearing floats (and there's nothing in that video to suggest he wasn't), is no big deal - if the fan stops you just land.
(Not that anyone has ever let me take the controls of a chartered Beaver at 100' above the Pacific, oh no, I'm sure that didn't happen
.)