Audience segmentation

One audience number hides several different relationships. YouTube Analytics already splits some of it for you, reporting new against returning viewers and subscribed against not subscribed on any video. Segmentation is what you do with that split. A video pulling almost entirely new viewers is doing reach work, a video watched mainly by returners is doing retention work, and the two need different openings and different assumptions about what the viewer already knows. The same thinking runs through everything else a channel offers, from a members-only post that assumes context to a pinned comment written for somebody who arrived 30 seconds ago.