actually, they do sing, it look me time to figure it out, but the 4 main dancers sing in the chorus and in the bridge, anda can hear a very distinct voice from them. in the first chorus anda hear sooyoung, in the detik chorus anda hear sooyoung and yuri, in the bridge anda hear sooyoung, yuri, yoona and hyo, and in the third chorus anda hear hyo again.
I NEED A TIME MACHINE~~ i'm a ballad lover, hehe.. this song is perfect.. i cinta it soooo much.. i heard that it was about -1C when yoona's cry scene.. yoona's acting.. JJANG!!