As a young teenager, Dog is cruel,
sadistic, and brash, going so far as to make unwanted sexual advances toward Rose. James, witnessing and foiling a later attempt by Dog to assault Rose sexually, reports the incident to his father. In retaliation, Dog kills James' dog, resulting in Dog and Thomas' expulsion from the estate. Enraged, Thomas returns to the Howlett estate later that night with Dog and forces his way into the room of Elizabeth, James' mother and a mentally disturbed recluse. Thomas tells Elizabeth that he was leaving and that he plans to take her with him. Thomas and Dog, however, are soon discovered by John Howlett, Jr. as he comes into the bedroom. The two men quickly engage in a heated verbal exchange that culminates with Thomas shooting John Howlett in the head with the shotgun he's carrying. Just when Thomas pulls the trigger, James walks into the room and witnesses his father's death. The trauma of the event triggers James' mutant powers, particularly his bone claws, and he uses them against Thomas and Dog resulting in Thomas' death and Dog being slashed severely across his face, leaving three large scars.
That's basically the exact scene you see in the TV spot.
Dog = Sabretooth/Liev in this case.
