From the FAQ:
Q: How do I choose a part to play from Tan Dun’s piece?
A: Go to the ‘Prepare’ tab of your local YouTube Symphony Orchestra channel
and select an instrument from the pull-down list. That will give you access to the sheet music for that instrument, and the opportunity to rehearse your part with the conductor video. All the parts will be compiled by LSO into a global collaborative video.
Q: How will you ensure consistency of sound quality, tempo and pitch?
A: We’ll be able to ensure the quality of tempo and pitch through the
conductor video that you can download from YouTube.com/Symphony.
More info here
