You could probably, with a little effort, put something usably like that together with a few sample libraries containing effects such as movement, etc, and some of the "noises : found on various sample instrument collectiond (knocks near a vioin bridge, etc - the Advanced Orchestra stuff has some of that), all through a nice reverb for the proper room. Actually there are quite a lot of "human" effects to be found for free on the net. lo-fi but ok for this purpose.
A cleverer alternative might be to record the few seconds before the start, or between movements, of a live radio concert.
-or, better still, why not order large amounts of pizza and champagne ( +beer for the tuba player of course) , rent the carnegie hall, and invite us all over with our instruments for the evening to breathe and bump into things as you direct.....?
For floor movement, as Evan said, you *need* to be in LA. You might also need to be very patient, though.
[[;)]]
Nigel