There were about 24 kids on the steps in the Sanctuary during his performance. McIver was the ONLY one who sang the 'huh huh' part leading into the chorus. (He tried to get his buddy Sam to sing along with him but Sam wasn't interested.) He'd been listening to the song on my iPhone for weeks and practicing and was very pleased with himself!
PS: Don't ask me where he got that accent for 'liiiiiiii-on.'