[Ralath]

HD SNSD - The Boys (White Shirt) Nov19.2011 GIRLS' GENERATION Live 720p - YouTube

Only Taeyeon, Seohyun, Jessica and Sunny would sing without voice overs.. all the overs had background music to cover them up...

Yoona especially obvious in her first solo part..

Well to be fair, those are the only 5 people that sing in this song... ahah..

And Yoona's part was originally Tiffany's, but Tiffany gave it to Yoona because Yoona didn't have a lot of parts or whatever.

This is hilarious!

[en] SNSD on Dream Team [1/5] (111113) - YouTube

Yeahh!!! I found that too but haven't watched it yet.