In a significant departure from its previous policy of allowing only video clips that are less than ten minutes long, YouTube said Friday that it will allow "select content partners" to make full-length episodes of TV shows available on its website. In a further policy departure, the website said it would allow advertising on the videos as part of its revenue-sharing agreement. One of the first media companies to sign on was CBS Corp., which said that it will make available the season premieres of Dexter and Californication from its Showtime pay-TV channel, as well as a number of "classic" TV shows, all of which are already posted on