Ben Shephard interviews the cast of the latest Harry Potter film - Daniel Radcliffe, Emma Watson, Rupert Grint, Julie Walters, Bill Nighy, Tom Felton and Jason Isaacs - and discovers how one of the most complex scenes in the series was put together. Ben also learns how the flying sequences were shot, hears stories of friendly competition among the main stars during filming and gains an insight into life on the set of the new movie