'All I Want for Christmas' Carpool Karaoke Video - featuring Mariah Carey, Adele, Lady Gaga and other guests

'All I Want for Christmas' Carpool Karaoke James caps off 2016 with a Christmas edition of Carpool Karaoke featuring Mariah Carey, Adele, Lady Gaga and other guests throughout the year to sing Mariah's classic "All I Want for Christmas Is You."