DBSK [Mirotic Concert] - Opening + HEY! (Dont Bring Me Down)

Song: HEY! (Dont Bring Me Down)
Singer: DBSK
Album:

it's not that i'm judging and all, coz i know they have great vocals.. and the dancing is hard..
but i am really disappointed coz it's the opening song and they're lip-singing...
i don't have a singing voice, but by watching this and knowing that they are lip-singing, i couldn't enjoy it at all..