When you do a specific movement you can avoid fall damage that normally kill you.
If you do an air strafe : go forward and left/right while on air and moving your crosshair in the direction of where you want to go you can land on the ground and don't take any fall damage. This bug is quite hard to do but with somes tries you can actually did it.
I maked a video of it but i can't upload it there. Can i send a link there ?
I do not speak english very well so i'm sorry, thanks for reading.