How did the Nepal debris flow get so big, and what's important about the Border Port video?

The Nepal rock and ice fall and resulting debris flow will go down as one of the largest natural disasters in modern history. Significantly, much of the disaster's unfolding was recorded by witnesses, allowing a glimpse into the incredible power that mountains and water possess. This video talks about some aspects of the event that show its true physical scale, as well as how the debris flow became so large without an introduction of large amount of water at its beginning, such as from a lake burst event. The event is also compared to a similar, but smaller, failure in Himalayan India that occurred in 2021.