Definitely the best interview in the US. Kelly and Michael knew their background. And Ylvis just responded well. They're smart and funny! Simply adorable!
He sure did stop him, I wonder why. I always like that they explained its a joke for the people who try to say omg how dumb they actually think they are good, who don't realize they actually are musical geniuses and are very good with musical comedy! They live to make people laugh and unlike some/most comedians are actually very very talented in music, and very smart.
I strongly recommend you (as big Ylvis fan from Poland) see another their songs like: Cabin, Stonehenge, Someone Like Me, Trucker's Hitch, Mr. Toot, My name is Finn etc etc etc They are comedian and they have so funny pranks, interviews with strange people, great funny talk show - not focus on this one song :)
I'm surprisingly impressed by Bård and Vegard that it didn't go awkward, like it almost always does when you hear someone you know "everything" about is being interviewed for the first time abroad lol. They managed to escape or avoid pothole prompts (creds to the hosts a bit too I guess) like it was the 1000th identical clip.