Seulgi and Make It Hot Challenge.

Why Koreans care

The replies treat casual clothing as a way to appreciate movement apart from stage costumes. One viewer explicitly says it makes the dance lines easier to see: an informal-looking challenge can offer a different viewing experience, not merely a less elaborate version of the stage.

In the Korean comments

Fandom, controlled ease: “SEULGI is the very definition of clean and effortless.” Minority, preferring casual styling, excerpt: “Stage costumes are great, but dancing in everyday clothes like this shows the dance lines better and feels satisfying.”

What the words mean

작두탄다 (jakdu tanda, performing with extraordinary flair) literally evokes riding a blade but praises SEULGI's inspired dancing here. It is not describing a dangerous stunt or saying that an actual ritual took place.