To make things even more interesting, because of the overly long copyright, everyone's clinging on to anything they can. As a result a lot of stuff is buried and most likely destroyed by the passage of time (how many CDs have you had that can't be read anymore?). Say what you will about piracy, but it can surface interesting things people and companies are hoarding in the undefined hope that sometime in the future they will become valuable again.

Examples:

* source code and assets of games made in the 70's, 80's and 90's: very often you can see even the companies that made these games unable to re-build these games, because they lost the source code (!)

* documentaries from many broadcast networks