We admit to being lukewarm about the "Harry Potter" franchise, but we know we're in the minority. Folks loved this series so much (and spent so many years loving it) that we suspect the mourning period may be lengthy. It may be hard on the cast, too, as demonstrated in the trailer for "When Harry Left Hogwarts," a documentary shot during the filming of "Deathly Hallows." Fond-farewell fan mementos are nothing new, but what might make this one revealing is that Daniel Radcliffe and the gang seem acutely aware that this crazy, amazing 10-year ride is all about to end. They seem genuinely worried that this could be the highlight of their careers, something they'll never be able to top. Pretty sobering thoughts for people just barely into their 20s.