“Jurors ordered Tenenbaum to pay $22,500 for each incident of copyright infringement, effectively finding that his actions were willful. Under federal law, the recording companies were entitled to $750 to $30,000 per infringement. But the law allows as much as $150,000 per track if the jury finds the infringements were willful. The maximum jurors could have awarded in Tenenbaum’s case was $4.5 million.”