Uh, I think Buggles’ exegesis is canonical in this matter: http://www.youtube.com/watch?v=Iwuy4hHO3YQ
Channeling/impersonating my best Marshall McLuhan, sound is not made richer by video, but rather depleted universally . Video is cool; Audio is hot.
However, the media-sensory balance of “listeners” has shifted. Music as we knew it just a decade ago from the better part of the late 20th century is an nostalgic archaic obsolete media form, an exhausted defeated project. YouTube upcycles “music”, more specifically, music’s projects (ex: The Many Deaths of Punk http://souciant.com/2012/10/the-many-deaths-of-punk/) for further cultural refactoring.
Bonus: YouTube killed the Video Star http://www.youtube.com/watch?v=hi27gx-a3lg