We are together , a song from album 'Chapter II' . It does not have official mv like Why Goodbye, but it has amazing dance practice (they're always stuck by funny moments, it   happens here there too XD ) 

Who is who : Mika ( black  curly hair, and long  pants with light grey  blouse, and red-white sneakers shoes ) karam( dark-purple blouse with white stripes and blue white  shoes) , Hyunmin ( the one with  khaki/dark grass coloured jacket and dark pants with white shoes) , Injun ( the one in jacket in yellow- dark blue colour and dark green pants with white shoes ) , jay ( dark hat,  dark grey coloured jacket, white tshirt, black pants and black shoes ). Hope the description helped to recognize The Boss ^^

where they appear  : 

1. InJun : 1:09  ( he is the first one in the column) 

2. Hyunmin :1:12 ( the one who forgot to turn on the song XD)

3. Jay 1:15 ( the one boy who's face is showed as soon as Hyunmin  went out)

4. Karam 1:26 (the one who 'crawled out' of the column

5. Mika 1:25 ( he closes the column ; his back is visible, the one in light grey  blouse :) )

credit: to the rightful owner of the video :)