I watched the finals this evening, and fast-forwarded my Tivo once it got down to the last two boys and I realized they knew all the words. At that point, it wasn’t particularly interesting.
I also noticed something else. I did not see a single obese, or even really chubby, youngster among them, at least the ones who were shown on television, and not much of that in the audience either. 
Maybe some of them lost weight because they knew they would be on TV; IDK, but I’ve observed that in past years too.