http://www.youtube.com/watch?v=BjK7-fi5mZs&list=UU6ZFN9Tx6xh-skXCuRHCDpQ&feature=player_detailpage
Death, resignation and high-profile jobs have resulted in an unusual number of newly competitive Senate openings. Roll Call's Shira Toeplitz and NewsHour political editor Christina Bellantoni walk through the political cause and effect of congressional vacancies in Massachusetts, Hawaii and South Carolina.