I am sorry to say that, but copyright protection time should vary on the subject. Programming books - 10 years maybe? 10 years is ages in computer science. TV shows? 5-7 years maybe. After that time nobody wants to pay for watching old big brother or another Fort Boyard... Nor pay for storing it in archive. And this is the culture other creations are referring to.

We've run in Poland into very strange situation - Polish Public TV (TVP) paid for the great dubbing of some Disney shows. They recorded it on VHS which were overwritten by other shows. Now the translation and the dubbing is lost, found sometimes on people's home recorded VHS but in poor quality, because recorded from the aerial.

Many original episodes of Dr Who were destroyed by the BBC, some have only been recovered because of "pirate" home recorded VHS, or people that "stole" tapes from the dumpster.