The introduction of the home video and Internet saw a boom in the worldwide porn industry that generates billions of dollars annually. In Japan, point of view pornography is referred to as hamedori . Studies among BDSM practitioners in the US have shown that about half of all men find the idea of bondage to be erotic; many women do as well. The current public acceptance of celebrities with sex tapes is speculated by naked milf Joe Levy, executive editor of Rolling Stone, to gay cock be due to the easy availability of pornography, as well as couples more commonly making their own tapes due to the prevalence of video cameras. Reality and voyeur pornography, animated videos, and legally prohibited acts also influence the classification of pornography. Following the introduction of the Motion Picture Association of America film rating system, independent animation producers attempted to establish an alternative to mainstream animation. The queening stool is also related to a smotherbox, which also allows the person under the seat to be locked in place, restrained by the neck as in a set of stocks. A woman can use a secondary vibrator, between the dildo and her genitals, to get pleasure from pegging. Today, pornographic films can be sold or rented on DVD, shown through Internet and special channels and pay-per-view on cable and satellite, and in adult theaters. Such documents have not been recognized as being legally binding, nor are they intended to be. A related term used in the genre is the term cougar, which implies an older woman as predator. Women with women Main article: Lesbianism in erotica: Lesbianism in contemporary pornography Lesbian or girl-girl pornography features women engaged in sex together, but is typically aimed at a male audience. Such grounds and even the definition of pornography have differed in various historical, cultural, and national contexts. The term is typically used by the cinematographer within the narrative framework of a pornographic film, and since the 1970s has become a leitmotif of the hardcore anime hentai genre.