It doesn't open until midnight tonight, But Harry Potter and the Deathly Hallows Part 2 has already set a record. Warner Bros. said on Wednesday that the movie had sold $32 million worth of tickets online in advance with many of tonight's midnight screenings already sold out. That represents the biggest advance sale for any movie in history. Meanwhile box-office forecasters are claiming that the film has a strong chance of setting a weekend record at the box office, breaking the one set in 2008 by the opening of The Dark Knight, which recorded $158.4 million in ticket sales. Not only does it have 3D surcharges going for it, but its relatively short length -- just over two hours -- will permit theaters to increase the number of showtimes for the movie. More than 3,800 theaters will be screening the film tonight, increasing to 4,375 on Friday. Some 3,000 of those theaters will be showing it in 3D.