I figured out the time and place Mike and his gang went to the party (It was September 3rd 2010, even though his alarm clock in the short says September 10th 2010)
The band they saw that Mike made fun of was La Dispute. I can tell because they have whiny singing and how all the instruments are the same except the bass was replaced with a tuba. This is one of the two videos taken at the party.
https://www.youtube.com/watch?v=oD7qrEUxIq8 
