A video of Sumner Redstone that surfaced as part of the CBS-National Amusements court battle is being cited in a different dispute — one involving the aging mogul’s former companion.

Manuela Herzer has asked Los Angeles Superior Court Judge David Cowan to revisit the question of Redstone’s mental capacity, claiming it’s key to determining whether she was wrongly denied a chunk of the mogul’s fortune.

A hearing has been set for August 30 to consider her request for discovery.

Herzer cites the video to make her case that the 95-year-old Redstone is incapable of making his own decisions. That video, shot by movie producer Arnold Kopelson, is expected to be used to bolster CBS’ claim that the elder Redstone no longer is in charge of National Amusements, the family’s holding company.

Redstone’s former companion told the court that she expects Kopelson to testify that Redstone is “unable to communicate, unable to understand when he is spoken to and appears to lack capacity,” according to the Aug. 15 filing (read it here).

“Herzer has not been able to obtain any information regarding Redstone’s condition and capacity for several years because Redstone has been sequestered at his residence out of public and the court’s view,” she argues in court documents.

The Kopelson video sheds new light on Redstone’s condition, she maintains.

The question of Redstone’s capacity also has become an issue in CBS’ dispute with its controlling shareholder, National Amusements. The media company’s lawyers contend that daughter Shari Redstone has taken advantage of her father’s diminished capacity to pursue her own agenda for CBS and Viacom.