I don't have no problem with screams, as long as they're reciting lyrics, but all of this yelling, squeaking and even loudly talking to each other is a no go. But the audience should be allowed to cheer, to boo (not that I've heard any boos) and to sing along to it. And the shouting of the line "if you don't like my presence, why did you invite me" definitely predates his pre-teen idol era, I believe, they did it last year at festivals as well. It's also normal for a festival act to point the microphone at the crowd and let the audience shout the punch line. No problem here. And some festival goes don't really sing, they just shout, you can't sing through all 6 or 7 acts you're watching.
