This has to be the coolest Flashmob of all time
and it comes with one of the best comments i've ever read on Youtube:
"Yes, this brought tears to my eyes. This represents some of humankind at its finest: Talented musicians having spent a lifetime mastering their instrument, coming together to coordinate for a few weeks, and then makiing it available for all of us to hear for free, live or, thanks to the technical geniuses, here on YouTube. This reminds me of the good side of humankind."