As for Taylor Swift, she won the award of the Best Video for I Knew You Were Trouble, and thanked "the guy (she) wrote the song about" for being the cause of this award. It's obvious she was talking about One Direction's Harry Styles.
Again, when 1D got on stage to accept their award of the Song Of The Summer (Best Song Ever), she was caught whispering something to Selena Gomez. Rumour has it she was once more mocking her ex.
But Miley Cyrus' number with Robin Thicke was definitely the most shocking thing that happened at the ceremony. The singer was performing Blurred Lines, when Miley started dancing inappropriately, wearing a latex short and t-shirt.