Available on DVD, this sharply argued documentary “Roman Polanski: Wanted and Desired” isn’t about the innocence or guilt of its title subject, who after pleading guilty in 1977 to having “unlawful sexual intercourse” with a minor flew from Los Angeles to London, never again to return to America. Neither is it about Mr. Polanski’s likability, his tragic past, morals, short stature, brilliant and bad films, the sleaze factor or your personal feelings on whether there’s anything wrong with a 43-year-old man’s having sex with a 13-year-old girl. All these elements come teasingly into view here, but really this is a movie about a very different kind of perversion.