Sure, every online property is a place for ads. However, in this case content producers don't have to say "Subscribe to my YouTube channel for new videos. Oh, and if you want updates follow me on Twitter. I also share pictures on Instagram. And if you're looking for upcoming events, check out Facebook...".

Not like anyone who is already doing that is going to stop, but Google is hoping that maybe there will be a shift towards doing it all in one place, particularly if video is their primary medium.