YouTube orchestra - improvisation opportunity

[Andrew Gleibman]

Did anybody try to participate in this endeavor as an improviser?

 

http://www.youtube.com/watch?v=cvAhGH9fHD0

 

I spent almost an hour trying to understand when one should start and finish the improisation, but did not succeed. The terms and the deadline for the submission are also unclear. Though, the project seems to be interesting.

[Greg Brus]

This might give you a hint:
http://www.youtube.com/watch?v=aD3fyUOyXqA
http://www.youtube.com/watch?v=QolK8EGdFeI

[Andrew Gleibman]

Yes, thanks, probably they assign green triangle for starting, "||" for pauses, and red quadrangle for stopping the improvisation.