"Every night of the All State Choir conference at about 11pm, everyone comes out to the balconies of the 18 story Hyatt hotel to sing the National Anthem," so this is more tradition than Olympic-fueled display of patriotism.
Here's a better video from last years, you see more of the balconies, wow.
http://www.youtube.com/watch?v=OAEmpdSHC10#t=93