I saw this video a long time ago, but really didn’t watch it until just now when I was browsing around Binary Moon, the same site where the “Old School” (Regulus) theme is from. The video is of Legend of Zelda music being performed at some symphony. It’s possible that it was not Nintendo endorsed, but I doubt it (pretty sure Nintendo would have to have its hand in there somewhere).
At first I thought it was from a Nintendo CD, specifically the Smashing! Live concert in Japan around 2005. But that couldn’t be it as the music drifts off from the LOZ song featured on the CD. So then it must be just a regular Nintendo concert (Why doesn’t Seattle get one of those? I mean we are right next to Redmond, and Nintendo is near there. Seriously).
Anyways, the music is really great, despite the horrible filmography (stop shaking the camera!). I think you might enjoy it.