Fair enough, I suppose it depends on how broad your categories are. Personally, I absolutely consider YouTube a video-based social network. You follow people/b

Fair enough, I suppose it depends on how broad your categories are. Personally, I absolutely consider YouTube a video-based social network. You follow people/brands, have at timeline, can contribute comments on what they post, etc. It doesn't tend to have as broad a social graph as something like FB, but almost nothing does. Twitter (for example) also has a large number of popular public accounts, similar to YouTube.