Justin Bieber and Mariah Carey take on the roles of holiday retail elves in the breathlessly awaited video for their “All I Want For Christmas Is You” duet, singing the yuletide pop classic before handing out gifts to lucky fans in a shopping mall bedecked with Christmas cheer. It rolled out in holiday style too: the search-engine beloved teen heartthrob introduced it live on NBC’s Christmas In Rockefeller Center special. Watch the Sanaa Hamri-directed clip below and see if the “festive collabo” is naughty or nice. More »