Wow! The ghosts are back. Man I remember my friends and cousins telling me storys of them and showing me videos on them. I spent so many hours on Halo 3 trying to find The Ghost of Foundry. Good memories. T^T
Honestly doesn't look like the guy was doing anything wrong intentionally. The sliding was probably just a glitch, happens in a few different games. He was still moving at normal speed and died the same. Looks like he went in tunnel to try and escape, got stuck and jumped off only to find himself in the roof.