Smart says Mitchell based some of his assaults on scenarios depicted in pornographic magazines.
"He would turn, and he'd look at me, and he'd be like, 'Now we're going to do this,'" Smart said.
Smart spoke out against pornography in a new video from activist group Fight the New Drug, which raises awareness of the harmful effects of porn by presenting it "as a public health issue, rather than as a moral, political or religious argument."
"I have gone on to become an advocate for abuse prevention, an advocate against pornography. I witnessed firsthand just how damaging it is," Smart said.
Smart testified against Mitchell in 2010. He was sentenced to life in prison in 2011.