Touching fish can wipe off the slim coat leaving them open to infections, as the fish is going towards his hand I don't think it's stressing it to much
Fish doesn't appeared to be scared, or angry the movements aren't rapid or aggressive. Even the bites seem "half assed" if you will. Looks to be a learned behavior of some sort. Cool video. I've seen sharks act similar in different marinas, lemons and nurses that would come up on the wet docks to be petted and scratched and then fed the scraps from the fillets.
Beautiful GT. I would bet it's more stressful to the fish than not. He doesn't appear to be pissed but his breathing would indicate hes a little stressed or agitated to me. I don't think it's healthy for the fish touching him all for the owners pleasure.