It's every Trench song playing at the same time. Except "Love It Here", unfortunately, because it's not available on my account, and I quickly found out why when I started watching it on another account (It's LOADED with profanity, plus it's so painfully noisy that I couldn't listen all the way through)
Trench by Riji Monogatari and all their songs (except Love It Here), based on Splatoon Artwork by Riji Monogatari, from the April Fools pipecast
