Unfortunately, fangirls were the majority of the audience, so when the curtain dropped, hardly anyone clapped because they all had their camera's ready. You know the lead'll do their bows last, clap for all the people who spent the last two hours working to entertain everyone, jeeze. Then you can grab your camera and take pictures/videos. But, Yesung egged the crowd on to clap for everyone, and decided to pop up with some adorable.
Source: Myself; My Youtube