I had no idea until I stumbled across this guy’s clip. He’s assuming that YT management is choosing the featured vids based on their own preferences, but I’m not sure that’s true. It may be that they have an algorithm that looks for clips whose number of views is surging and then adds them automatically to the front page. A google search didn’t shed any light.
He seems surprised, though. He shouldn’t be. A screencap follows below.