All three dogs in this video are good friends and have been given a bone each. The black dog is guarding her bone from the brown and white dog from when it approaches, by growling at her. This is normal dog behaviour and should not be punished. The black dog is not trying to dominate the brown and white dog. The brown and white dog, sensibly, backs away because she is either not as bothered about the bone as the black dog is, or she has learnt from previous experience that it is not worth getting in a fight with the black dog because she will unsuccessful.