(CNN) -- British actress Thandie Newton, who joined crowds of demonstrators in London on Thursday to protest violence against women, said she knows the feeling of exploitation and humiliation from the "kinds of things I was expected to do in auditions."
Newton recalled one incident as a teen, when she was exploited in a "casting couch" style interview, which she said many young actors can be forced to endure.
"There was one horrific incident where I went back for a second audition," she said. "The director asked me to sit with my legs apart; the camera was right positioned where it could see up my skirt."
Newton said the director told her to "put my leg over the arm of the chair, and before I started my dialogue, think about the character I was supposed to be having the dialogue with and how it felt to be made love to by this person."
Three years later, Newton -- who was then married -- learned from a conversation with a producer at Cannes Film Festival in France that the director had used the video to entertain guests during late-night parties.
The London native has since starred in such films as "The Pursuit of Happyness" and "Mission Impossible II."
On Thursday, she was apart of the throngs outside Parliament in support of a campaign called One Billion Rising that seeks to raise awareness of the attacks that women routinely confront.
CNN's Max Foster contributed to this report.