I like to think the drummer in that suit’s been doing it all day, getting increasingly hot, going increasingly insane from the insipid kids songs, until they just snap and unleash the thunder.

Here’s a higher quality full length video:

https://www.youtube.com/watch?v=V8XrtVpxOEI

And the relevant know your meme page:

https://knowyourmeme.com/memes/nyango-star