Entertainment | TravelI recently ventured into the hollowed-out Virginia mountain where the Library of Congress keeps copies of every movie, TV show, and sound recording that’s submitted for copyright. Officially, it’s called the the National Audio-Visual Conservation Center. I call it Heaven. Here are stored, in specially built vaults, the highly explosive nitrate prints of films made prior to the 1950s…historic videotapes, including the first-ever color broadcast…vinyl and shellac discs dating back to the days of Edison… and in a lead-lined vault …