Media mogul Sumner Redstone can be deposed at his home in a short videotaped session ahead of a trial to resolve his ex-girlfriend’s lawsuit over his mental competence, a California judge ruled on Monday.

The recording of Redstone, the controlling shareholder of media companies Viacom Inc and CBS Corp, will not be seen by the public, Los Angeles Superior Court Judge David Cowan said. A transcript will be released promptly after it is played behind closed doors, the judge said.

Lawyers for Redstone’s former companion, Manuela Herzer, had requested that the 92-year-old billionaire be called as a witness in the trial, which starts on Friday. Herzer claims Redstone was not mentally competent last October when he replaced her as his designated health care agent.

Viacom and CBS shareholders have closely followed the lawsuit for what it could reveal about Redstone’s condition. If he is declared mentally incompetent, it could trigger a seven-person trust, which includes Redstone’s daughter Shari Redstone and Viacom CEO Philippe Dauman, to take over the voting shares of Viacom and CBS owned by the Redstone family.

The deposition by Herzer’s lead attorney can last no longer than 15 minutes, with a further 15 minutes set aside for questions from Redstone’s lawyer, Cowan said.

The judge said he tried to balance the public’s right to view the trial with protection of Redstone’s privacy.

“Nobody deserves to have a career tarnished by having been taken to a courthouse and made a public spectacle of when he would not allow that to happen had he the strength himself to stop it,” Cowan wrote in the ruling. “The public will still know what he was asked, what he said in response and in turn the judicial process remains subject to scrutiny through the deposition transcript.”

Redstone’s attorneys say he has a serious speech impediment, but they argue he was fully aware of his actions last October when he named Dauman as his health care agent in place of Herzer. He later substituted his daughter, Shari, on the health care directive.

Pierce O’Donnell, Herzer’s lawyer, said he expected to take Redstone’s deposition this week and would use the videotape at the beginning of the trial. “Fifteen minutes should be more than enough” to establish Redstone’s lack of mental capacity, O’Donnell told reporters after a brief court hearing.

Redstone attorney Gabrielle Vidal, in a statement, said she appreciated “the court’s continued protection of Mr. Redstone’s privacy and dignity.”