Distribution is key to an artists success as it is down to the distributors as to who and how many people will be able to get hold of the music.
Many record labels distribute the music videos of their artists directly to sites such as you tube, however some make the decision to go through music video sharing websites such as Vevo, in turn Vevo then distribute the videos to you tube.
Many artists have their own Vevo channel on you tube specifically for the distribution of their videos to the general public.