Can't disagree with the comments so far. There used to be a time when YouTube users would steal content from Newgrounds, without credit at all. Then we allowed embedded video streams from YouTube and some other sites, membership here picked up a little, but by then, membership as a tend dropped off.
In the past decade or so I've brought up the subject of Newgrounds, to people under the age of 30, and a slim majority of them knew about our site. Many of them went away, along with the indie software developers (who went to Steam, since Flash was and is being mismanaged), but still liked the Art Portal.
NG has always been just below the surface of the internet, and that's okay. Somehow this place is still relevant in many ways. At least the members here review content and collaborate on content together. Many other MSM sites don't have that kind of heart or loyalty to it's membership.
AliceMako
Content proliferates the same way everywhere, people link things then they end up in different places for starters.
Things get reuploaded, licenced out, sold off, stolen or handed to spreaders and statwhores to farm traffic. Something really typical is for people to post their content in multiple places to begin with in hopes of maximising their revenue stream.
Newgrounds is like the original proof of concept everyone their grandma and their dog included copied, it's never really been mainstream even at the peak of it's popularity though any rube can tell you we wouldn't have a mainstream as we know it today if it weren't for newgrounds.