어 추다

dance, dance along to something

추다 exists almost entirely inside "dance a dance", 춤을 추다, and here it follows an "-아/어" form. Most lines are 따라 추다, "dance along, copy the dance": wanting to copy the dance through the window, everyone copying this one a lot, captions reading "dancing along" and "copying the millstone dance". One line is 이용해 추는 춤, a dance done using the thigh and glute muscles. Watch out for the first line: 보내 췄어요 is not this construction — it is 보내 줬어요 "I sent it for him", spelled the way it sounds.