I didn't immediately realize that the ball was the source of the sound, but even so, it's a bit hard to believe that it wasn't added on top... Interesting.
Because such a metal plate only produces one note.
And in the video, some plates produce one note, while others produce two. Starting at 00:35, this is especially noticeable.
But I understand that you can't play this melody with just one note. Maybe it could be done with two balls.
However, it's still much better for the contest than a string of profanities with Raiden, and it would have received a higher rating from me.

В тихой однообразной жизни всегда так бывает: каждый отдельный день бесконечно долог, но месяцы и годы мчатся с непостижимой быстротой.
I wanted to offer you some flowers, but a crown would suit a princess like you much better
Смысл жизни в том, что жизнь на тебе не заканчивается