Environmental kills are incredibly valuable in Overwatch because players don't need to do a lot of damage or focus down healers to get them. Environmental kills are also pretty much the only time it's possible for players to get multiple kills at one time without needing to use an ultimate.
Certain maps like the Ilios Well are so well-known for the ability to get environmental kills that heroes like Lucio, Wrecking Ball, Roadhog, and Orisa see much more play than on other maps. There are two sets of heroes that are usually played on these maps: those with movement abilities that allow them to save themselves and those that can get environmental kills.
The video, which was posted on Reddit, shows a Lucio get many environmental kills over the course of a game until all but one member of the enemy team quit the game. The strange part about the video is that the enemies take the riskier path to the point every single time and many enemies are playing heroes that should be able to stop themselves from being knocked off the map including a Lucio, Hanzo, and Orisa.