Tenenbaum said he downloaded and shared hundreds of songs by Nirvana, Green Day, The Smashing Pumpkins and other artists. The recording industry focused on only 30 songs in the case.
The music industry has typically offered to settle such cases for about $5,000, though it has said that it stopped filing such lawsuits last August and is instead working with Internet service providers to fight the worst offenders. Cases already filed, however, are proceeding to trial.
Tenenbaum testified that he had lied in pretrial depositions when he said his two sisters, friends and others may have been responsible for downloading the songs to his computer.
Under questioning from his own lawyer, Tenenbaum said he now takes responsibility for the illegal swapping.
"I used the computer. I uploaded, I downloaded music ... I did it," Tenenbaum said.
Associated Press writer Jeannie Nuss contributed reporting from Boston.