I think it's most likely that snake was already dead and the dude just stuck his leg into it. It's not an anaconda, it's a reticulated python. You can tell the snake was already dead because it was limp and deflated, lacking any strength that even a starving snake of that size would have. Constrictor snakes do not begin to eat unless they are certain their prey is dead and they also understand size so it wouldn't have been even trying to eat prey in a hole like that as there would have been no room to constrict and kill him. Snakes take a while to eat, it wouldn't have gotten that far up his leg without ample time time to remove it and the snake wouldn't keep swallowing if the guy was moving. Also, there were no wounds on his leg nor blood and there would have been lots. To top it off, the snake didn't bleed when they cut into it, dead things do not bleed.