This reminds me of those vids showing people who don suits/gear and launch themselves from mountains to mimic flying squirrels. I don't recall those vids documenting a successful landing
Insane.... A guy working for me says he has too little fear of height as to have it be dangerous. He is NOT into climbing or anything. Simply born with too little fear of such situations. So maybe that is the case with this guy in the video?
I would say that there is a combination of factors at work. Yes, climbers develop an immunity to the "fear of heights" (I know I did.). However, there is a subset of climbers who expose themselves to risks that are unacceptable to the mainstream of climbing. Google "Dan Osman" or "Dean Potter" to see highly-skilled climbers who could not find satisfaction via traditional climbing. In Osman's case, the result was death.
Daredevilism will always be an attention-getter as well. The individuals who publicize stunts like the crane climb want recognition as much as inner fulfillment.
Heights don't bother me and I wouldn't mind leaning over the edge without a harness, but there is no way I would hang from a rail, even with two hands.