The song/album is so boring, the people in it trying to sing the song can't be bothered to give a shit.
The boys are all high out of their minds and Taeyeon has a look of utter despair on her face. Her eyes scream, "KILL ME PLS" but no one can hear her.
Actually, the only one who's mustering a semi-positive emotion is Krystal... But that's probably because she's thinking, "LOL THIS SONG SUCKS COCK BUT AT LEAST I'M GETTING PAID TO JUST LOOK GOOD AND NOT SING IT ANYWAY."
That method acting tho.