Starting at 5:21

Starting at 2:26

Starting at 0:47

I think Kangin went to tap Donghae and they both went to Hyoyeon. Donghae trying to talk with Hyo but Kangin drags her (and yuri) away. 

Donghae gets halfway and sends water in their direction. Jealous Hae XD

Minutes later they came back and hyo start dancing all weird and donghae came to join her XD.

Dorky couple XD

Edit: I think the guys were all lovey-dovey with her because it was her birthday in that day. XD