In case it's not clear, that video is from the smaller rockfalls later on day one, not the fatal one. It must have been terrifying to be anywhere near, wondering how much more would be coming down and who, if anyone, had been affected.
The following day was the biggie, which took out some of the route the guys in that video had been climbing.
Webcam timelapse (view the inspiration point camera, from the 28th September, rockfall around 28 seconds).
View from Middle Cathedral.
Greg Stock, YNP geologist, estimated this one as a shield of rock height 120 meters, width 45 meters, and thickness average of 2.5 meters with areas up to 8 meters (26 feet), giving a volume of 10,250 cubic meters and mass of 27,675 metric tons.
It reached the road but, amzingly, only one person was injured.
It has obliterated sections of some esoteric aid routes and
Favresse and Ninov's Lost In Translation.
The Prophet and
Secret Passage and the East Buttress appear not to be directly affected, though who knows what flying debris may have done to the lower sections of those routes.