They just weren't as rich as Youtube, oh well, you can only break the law if you operate at a certain scale.

They are both fantastic in their own way. I don't think one substitutes for the other, really, if I love a book I would like to have the two for the two very different experiences. That said, ebooks are the right medium for "disposable" content, if there is such a thing, for example if someone has a book about "how to promote your company on Twitter" chances are it has a half-life of 6 months and would be perfectly stupid to have as a hardback. If, on the other hand, King Lear is available in a hardback edition, the use of an eBook version would be very limited, perhaps just to look up something quickly or enjoy the book when traveling.