Police found a video of Robert Manson, 61, wearing make-up, a short red skirt and black bra committing a solo sex act in front of a camera.
The sound track reveals him making obscene remarks addressed to one of his young victims.
Manson, of Edinburgh – who appeared from custody – admitted charges of indecent assault, sex with an underage girl and indecency.
The offences were committed at addresses in Edinburgh between November 1979 and January this year and involved three girls and a boy.
Two of the girls were only nine years old and the other was in her early teens. The boy was ten years old.
Advocate depute Andrew Miller, prosecuting, told the High Court in Edinburgh how police raided Manson's home in the Broomhouse area of the city in connection with another inquiry and seized a number of disks, digital cameras and other equipment.
Some showed how Manson had made one girl dress up as a model or belly dancer or rock star during their "games."
Other footage showed Manson simulating sex or committing other indecent acts.
The court heard that when one girl was 13 years old, Manson showed her a film of them having sex.
Judge Lady Stacey added Manson's name to the sex offenders' register and called for background reports.
Manson remains in custody pending sentence in Perth on May 20.