Actually alligator snapping turtles can’t extend their necks very far, so the person in the video isn’t in danger of being bitten so long as he keeps himself far away from the turtle’s mouth. Common Snapping Turtles, on the other hand, can extend their necks, and although they cannot reach nearly everywhere they are more than willing to lunge at anything that comes near their face. Here’s a helpful video that compares these two badass reptiles:
I won’t be swimming anywhere in Florida regardless.