The auditions are over. The first YouTube Symphony Orchestra - selected by viewers of the Web site - will consist of more than 90 musicians from some 30 countries, one of which is Israel. More than 3,000 videos were submitted by amateur and professional musicians from 70-plus countries. Musicians from professional orchestras, including the London and San Francisco symphonies and the Berlin, Hong Kong and New York philharmonic orchestras, picked 200 finalists. The winners were then selected by voters on YouTube. The selected musicians, ranging from ages 17 to 55, will participate in three days of master classes and rehearsals next month, culminating in an April 15 concert at Carnegie Hall conducted by Thomas, the San Francisco Symphony's music director.