Not sure if I'll ever end up using this, but even if you don't need a vocal crowd sound it's still an interesting and creative little trick. 
 

Cool! Thanks for sharing!

Nice idea to use a voice track ( stadium crowd) as the carrier in a vocoder application. Makes me think other voice carrier options (whispers, wails and screams, coughs, choir drones, etc) would work well for certain vocal effects. Good stuff - thanks for posting Sharke

nice production trick.... beats hiring a stadium crowd...

Think about this too. The carrier does not have to be stadium size crowd either.  Could be a nice tight group of say 50 people all cheering and getting excited at once.  The sort of thing you come across on sound effects libraries.  Then modulate that using your vocals and I am sure the end result will still sound like a large group doing a harmony part but very realistic at the same time.  Not so stadium like this time.  But I do like the stadium effect.  I have got some incredible aussie rules crowd cheers and roars with over 80,000 plus.  Nice big wide stereo recording too from well away as to hear its enormous size.