I do not know what I am talking about here. Well that is, I don't know from personal experience. But, from what I have read, the guy would have felt almost nothing. When you fall into a pot of boiling water, two things will happen. First, your body goes into shock and shuts down. In this condition you feel nothing, because the sensations overwhelm the nervous system to the point that it stops working. Second, you die.
These two things happen in such quick succession that you don't feel much of anything.
I've heard a similar thing about being burned alive. The pain of the experience depends on how quickly it happens. If you were thrown onto a bonfire, for example, you would die so quickly that it would be relatively painless. That is similar to what happened here. When he fell in head first, it would be over so quickly that he really wouldn't have time to process much pain.