Ravi also posted a message on Twitter about the incident.
"Roommate asked for the room till midnight," Ravi tweeted, according to prosecutors. "I went into molly's room and turned on my webcam. I saw him making out with a dude. Yay."
Prosecutors charged Ravi in a 15-count indictment in April. They accused Ravi of trying to hinder the investigation by altering and erasing his tweets and other transmissions.
Ravi could face up to 10 years in prison if convicted on the most serious charge of bias intimidation. Prosecutors would have to prove he targeted Clementi because of his sexual orientation.
Clementi's parents, Joseph and Jane, and older brother, Brian, sat in the back row of the courtroom. Ravi never looked at them.
"Our family is grateful for the active work of the prosecutor's office in this case," Joseph Clementi said in a prepared statement after the hearing. "We are eager to see the criminal-justice process move forward."
A second defendant in the case, Molly Wei, agreed to testify against Ravi, and could have her charges dropped as a result.
Wei, 19, of Princeton, is charged with two counts of invasion of privacy for letting Ravi use a computer in her dorm room to stream the video.
At a May 6 hearing in Middlesex County Superior Court, Wei admitted her role in the secret recording, waived her right to have the charges against her presented to a grand jury, and agreed to enroll in a pretrial intervention program. She declined to comment after the hearing, but her lawyer said that she was cooperating with authorities and that she should "not be a poster child for this."
All three students were freshmen at Rutgers University's Piscataway campus. After Clementi's death, Ravi and Wei withdrew.
Clementi's death attracted national attention, becoming a cause célèbre for gay-rights groups and an argument for tougher anti-bullying laws.
Ravi has been free on $25,000 bail since his arrest in October.
Altman told the judge that he had only begun to wade through evidence in the case, which includes 1,600 documents and 88 computer disks of material.
Contact staff writer Joelle Farrell at 856-779-3237 or at firstname.lastname@example.org.