If we didn't have Youtube available to us, that would mean we'd have to resort to our entertainment in other ways. For those who use it to view TV programmes, it would cause them to look elsewhere on other sites, potentially even leading to streaming/torrenting it...which is illegal.
For those who use it primarily for music (such as myself), we'd probably have to actually go out and buy soundtracks, or find other sources for it, which may or may not be legal (as the above).
And for those who use it to watch stupid stunts being pulled on a regular basis - then it sucks to be you.
Conclusion: Youtube is our barely-legal source of ultimate entertainment! Cable TV has nothing on it.