Well, it's a pop "version" of rap - not true rap, but not slow enough to be be just "fast talking chorus". I dunno what else you'd call it xD
The girls themselves have called it a rap, too, so I suppose in a way you gotta call it what they do
It seems that TaeYeon has a really bad allergy to certain nuts and accidentally ate something with nuts in it while they were in the US - she had difficulty breathing and kept slipping in and out of conciousness but refused bedrest and just took some medicine so she could appear at the interviews....so the clips of her with a drooping head are her struggling to breathe and dropping in and out of conciousness..