You Tube- How does it work?

I enjoy it, but I don't quite understand it. With programs like Napster or Limewire you're sharing music or videos from your computer. Simple enough. But with You Tube who is doing the storing? Or more to the point if a user let's call him Bob puts a video on line and I save it to my "Favorite" I'm given the option to keep that private or public. So I assume if you look at my user profile that video will be in my fav's file for people to click. But what happens if Bob discontinues the video? Do I and anyone else still carry that on for others to watch or what? What my brain is trying to get around is if thousands favor a video than the host [You Tube} has to have something in place to keep track of all the users correct?

Youtube is just a video hosting site that allows you to share your videos with others; all videos are stored on their (now Google's) servers.

So if a user, let's call him Bob, decides he doesn't want one of his videos in the public domain any more, he (or she) will remove it. Anyone who has linked it to their favorites will just get a message "This video has been removed by the user".
It's not a p2p type application, like Limewire; the user computers are not directly connected.

I see. so while there can be thousands of links there is one controling host.

grinninggnome: Essentially; yes.

OK, how does that work? or more confusingly to me is the sites that let you sponsor TV shows for free. If a person has the complete season of Friends available one day and the next they're gone [and it's not like Lime Wire] what is the deal? I don't get the sharing idea on this scale.

The episodes of Friends are there one day and gone the next because the copyright holder has complained to YouTube and YouTube has got rid of them.

Its just a hosting site. Much like there are sites where you can upload your photos for people to view, you can remove them any time you want.