John Oliver, who had to resort to comedy after he realized he would never be a professional soccer player, is still completely obsessed with English football, and happy to spend an entire interview explaining the game's various leagues—premier, peasant, Downton Abbey—to a confused David Letterman.
"This is why soccer will never take off in the United States," he eventually says, giving up. "You can talk about it as long as you want, you eventually get to the point of an American saying 'What's the point?'"
Aside from talking about soccer, Oliver was there to promote his new... nothing, actually. When Letterman went to roll a clip, there wasn't one, because "I'm not in anything."
Dave could have showed Oliver hosting Last Week Tonight, but why? You basically just saw him host The Late Show instead.