    Sentence 1: For which show did Billie Piper tape an  introduction?    Sentence 2: For the Canadian broadcast,  Christopher Eccleston recorded special video  introductions for each episode (including a trivia  question as part of a viewer contest) and excerpts  from the Doctor Who Confidential documentary  were played over the closing credits; for the  broadcast of "The Christmas Invasion" on 26  December 2005, Billie Piper recorded a special video  introduction.