Simplify the following text for a Grade 8 native English-speaking person.
Original: Thomas joined-up with YouTube in 2009 to help create the YouTube Symphony Orchestra , an orchestra whose members were selected from 30 countries based on more than 3,000 video auditions on YouTube .
Simplified: In 2009 Tilson Thomas created the YouTube Symphony Orchestra to give a concert that could be watched on YouTube . The orchestra was made up of young players from 30 different countries .