Updated with Seohyun version – thanks to socha asd  for the tip

I must have replayed that over 10 times… >_<

Translation [credit: oniontaker@twitter]

Yoona: Beds really do need to be scientifically designed…
Lee Sunkyun: Of course! Being fully rested even if you don’t sleep for long, that’s science!
SNSD: A bed isn’t just furniture~!
Lee Sunkyun: The science of beds, Ace Bed
Yuri, Jessica, Yoona: Have a good jam [jam = sleep]

Update

Sources: soshified@twitter, oniontaker@twitter, yuldori801@youtube, PianoKidz@youtube