How can I use WordPress to get something like YouTube or SlideShare?

I want to use WordPress to allow users to share their creations, something like YouTube or SlideShare, where people can create their own channel, visitors can rate their creations, users can have followers, etc.

I've seen Buddypress, but it's not what I'm looking for (because it's more like a social network). Also I've been looking for plugins to get something like this, but I haven't found something which provides a result like YouTube or SlideShare.

Can you recommend me something that I can use as a beginning (even if I have to complete it), or if there are several plugins which can give a result as the one I'm looking for?

Thanks in advance.