@Kamelpov or, alternatively, the building is more than 5~10 years old. Odds are, in the last decade, bulletproof glass manufacturing would've improved a lot. I'm no expert on bulletproof building windows, but I do know that a lot has improved in regards to shatterproof car windows/windshields. 10, 20 years ago, a large portion of the injuries sustained in a major collision had to do with broken glass, and that's no longer the case (as much, anyways). I expect bulletproof glass to have improved similarly. Yes, one's a point impact (compressive strength is the major player) and the other is somewhat a matter of sheer strength in addition to compressive, but still, both are valued in safe glass materials.
As for him running down the stairs and being faster than the other guy, uh... I guess he was spending more time airborne than the other guy between setting foot on the ground, allowing him to accelerate downwards more? The limiting factor on how fast one moves down stairs is not how fast you can put one foot on the next stair, but how much you can avoid decelerating when you do so. The fastest method (ignoring bodily limits in terms of breaking bones, and assuming you can accurately have your feet land on a step and not on the edge of one where you can't balance) is literally to jump as far out as you can, land, and jump again. For these back and forth pseudo-spiral staircases, same thing, just turn around between jumps. His body is probably able to withstand such impacts, so he does have the advantage there.