We can think of no better way to cap off our Halloween coverage than to slash into the latest DVD installment of “Horror Pain Gore Death.” The fourth volume of the series features scenes from various gore movies, including “Opera,” “Nekromantik 2″ and “Hollywood Chainsaw Hookers” edited to soundtracks by thrash and death metal bands including Massacre, Benediction, Forbidden, Nuclear Assault and Destruction. Click “more” to watch scenes from “Mad Butcher” atop Destruction’s “Mad Butcher”; “N