I'm not too sure. The Pirate Bay gives 890 results for "VHS" but Karagarga (private tracker) gives 5776 films with VHS sources. I'm sure there are plenty of VHS's on YouTube but YouTube feels ephemeral with the possibility of a DMCA request at any time.

So some of it is being archived by a very small subset of the pirate population. It would certainly be a lot easier if we didn't have to do it so far underground.

And many of them don't.

Case in point: Even the BBC has managed to "lose" a lot of the early Dr Who (they taped over a lot of it before someone started thinking about archival), and have resorted to recovering some of it from versions taped from broadcasts, but bits and pieces are still missing and will likely never be found.

A large part of what has been recovered has only been recovered because of a lot of effort from both the BBC and volunteers.

This is a series with massive cultural impact in the UK.

Now consider all the less popular series that don't have scores of fans pushing to ensure as much as possible of it is restored and made available...