Dancing and Singing in Japanese

So we have been teaching Isaac a children's Japanese song. We finally were able to catch him on video tape singing the song. It is "M(oo) sew oon day" I am doing it phonetically, this is not how it is spelled. "Tay oh oo tay", So no tay oh, oo ey knee" You will hear him say some parts better than others. He also has a new dance move which looks like he is boxing. He saw it on a dance show and copied the move.