The single greatest "innovation" at YT was the monitization scheme and licencing deals that automatically shuffled ad revenue to the copyright holders, effectively solving the piracy issues while still allowing users to share whatever they wanted to whatever soundtrack (with some exceptions).

That innovation was mostly a financial one and probably could only have been brought about with the leverage of the existing Google ad network, and the critical mass of users using YT for music piracy. YT is a much better experience for it too.

https://www.youtube.com/watch?v=SxigNvJxGn4 Teenage Mutant Hardcore Turtles was one my favorite first memes. I was so saddened when the soundtrack was ripped out when I went to show my friends. I was pleasantly surprised to have the true sound track back after Google fixed the moneyz.

I remember a lot of the piracy situation improving sometime after Google took over. I remember YouTube as the place you could type a movie or show quote and find a clip for that movie or show quote. Now you're lucky if you find it on YouTube, especially if you find the original clip without any oddness to it.