First, the link: http://www.youtube.com/watch?v=xBlQZyTF_LY

This is, I feel, a remarkable feat of musicianship in which 10,000 musicians (supposedly--I did not count) came together to perform Beethoven's 9th Symphony.

I don't recall Beethoven writing it for quite so many voices, and to some, it may be over the top, but just knowing the issues with sound delay and the logistics that go into making a production like this happen, I feel this is a remarkable feat. For starters, how did anyone in the upper decks even see the conductor?

Does anyone know of any other unique and/or creative performances that may shed new light on musicianship, or like this one, are simply impressive to behold even if they are relatively "standard" takes?

They have a few pitching issues lol

The 1988 concert celebrating the 135th anniversary of the Steinway piano is on DVD. In it over a dozen pianists including Ruth Laredo, Stephen Hough, David Dubal, Grant Johannesen and Christopher O'Riley play Schumann's Carnival. Each plays a movement. (A couple double up.) I think Hough playing Replique is on YouTube. My favorite performance is of Shura Cherkassky playing the final Marches des Davidsbundlertanze. His performance is so close to the edge. He takes the ending so fast, that it seems everything is going to fall apart. He hangs on. I find it absolutely thrilling. I wish I had been there to see it live.

Here's another: 18 pianists lead by Jose Iturbi.

I'm a big fan of Eric Whitacre's Virtual Choir initiative. Check it out:
http://ericwhitacre.com/the-virtual-choir/history