WARNING: Understandable profanity is used in this incredibly startling video.
According to staff at Willis Tower, the cracked portion you see here was a part of the safety seal of the observation platform and not the glass itself. Still, that's the last thing you want to see when you're suspended that high in the air.
Kirill Oreshkin is not afraid of heights. He climbs to the tops of buildings, towers, and cranes without any safety measures and takes some intense photos. The photos are cool but the process is crazy.