Celebrating Nayeon's Birthday

In the Korean comments

One comment reads, in translation, “Wow, another upload. I’m so happy she’s doing challenges I thought we’d never get to see, even at the tail end of the trend.” Another connects the post with two occasions: “Belated happy birthday, and congratulations on opening your YouTube channel.”

What the words mean

최애 (choe-ae, “most loved”) is fandom shorthand for one’s favorite member or bias. The top comment defines it in place by following “You’re my 최애” (choe-ae, favorite member or bias) with “you’re the member I like the most”; the register is casual and affectionate.