Listen and watch the music video, the Japanese music video, the song release live stage performance (feat. uncomfortably long elongated intro), or dance practice video. Onward to notes:

Mnet is a big subscription music TV channel.
OK so the whole deal with 2AM/2PM: they were once an 11-man band called One Day and then they split in half. 2AM has been inactive since 2015, and 2PM has been on hiatus since 2017.
To get you a taste of what it was like, here's the trailer for the final episode of SIXTEEN. The comments are worth reading (yes, really!) as a kind of time capsule.
TWICE - Like OOH-AHH, their debut song.
The Fancy rocker hand sign bit. Also, check out how they've graduated from the small dance studio to the deluxe one with JYP ceiling lights.
SORRY MERRY-GO-ROUNDS DON'T HURT US
Sidechaining in action with Daft Punk.
we slipped and accidentally BTS
It was not the flute, I just have Intro: Singularity on a playlist with 134340 (which features flutes a-plenty) - CL
The "Russian Meme Song" in question is 7th Element, by Vitas. Here's the Croes Brothers' version (one of them, anyway).
I baked you a pie!

As always, remember to follow @StanOntology on Twitter for the latest episode updates.