He talks about the attempted rescue of Art Gilkey. This was one of if not the most famous attempted rescue in mountaineering history. Gilkey was incapacitated and was put in a sleeping bag for his climbing partners to lower him down the mountain. This was at a height of 7800m. These slopes were very dangerous, and this put everyone at risk.
One of the climbers slipped on ice and this had a domino effect on the others. The rope became entangled amongst all but 1 of the climbers and they all started sliding down K2. They were facing a certain death unless the fall could be stopped. Fortunately, Pete Shoening wrapped the rope around his shoulders and ice axe, and used the axe to stop them falling down 2000m to the glacier below.
Ed Viesturs talks about his admiration for this group. He said that read of this story as a kid.
In another video on YouTube he talks about his 1992 summit on K2. During an attempted rescue of a climber Viesturs and his climbing partner got caught in an avalanche. This was as close that Viesturs ever came to dying on a mountain.