I found it uncomfortable too, kept wanting to turn it off it it weren't for wanting to see their piano playing.
I wonder if they have been encouraged to play up that way following the "stardom" of children such as that Honey Boo Boo and the stories of what some parents give their children to give them a buzz so they perform better in child beauty pageants. Unfortunately the "hype" seems to being media attention and money.
A shame for a child with such natural talent for music.
Looks to me like a child on the path to crashing and burning and that's a sad thing.