could it be they lip-synced those songs?
EDIT: Hmm I'm listening to Genie, and I'm more convinced it's a lip-sync not a studio-recording put on as a pass-off to a live cos imo.. the verses are studio-version sound, but some parts of the choruses, like Yonna & Sooyoung's "solos" sound more prominent here than on the CD-recordings I've heard.
I could be wrong, but whatever.. that remix of Genie is hot lol