They change minor words in songs all the time, guess it suits their voices better. Anyways this is going viral. Already 1 million views in less than 24 hours!
Hated that they played Destiny fulfilled dust... and no Deja Vu, Telephone, Party or Bow Down/Standing On the Sun? But they did so good and the queen on the left slayed the Sasha Fierce songs.
I love the Video Phone and Halo parts 
