I bet Disney's lawyers can squeeze a lot more money out of municipalities for playing the music publicly in the first place than they can out of random citizens who are uploading to Youtube.
When you look at it from a legal "use it or lose it" and corporate risk perspective it's quite surprising that Disney didn't even sent cease and desists.
Edit: Of course you don't lose the copyright but your ability to litigate someone else's unfair use is a lot weaker when their lawyer can trot out a million examples that you were fine with.