Image description: a screenshot from the Wikipedia page for the Doctor Who TV series, with a user-added caption that reads "Preserve the media you can before it's gone forever." The Wikipedia article reads, "No 1960s episodes exist on their original videotapes (all surviving prints being film transfers), though some were transferred to film for editing before transmission and exist in their broadcast form. [88] Some episodes have been returned to the BBC from the archives of other countries that bought prints for broadcast or by private individuals who acquired them by various means. Early colour videotape recordings made off-air by fans have also been retrieved, as well as excerpts filmed from the television screen onto 8 mm cine film and clips that were shown on other programmes. Audio versions of all lost episodes exist from home viewers who made tape recordings of the show. Short clips from every story with the exception of Marco Polo (1964), "Mission to the Unknown" (1965) and The Massacre (1966) also exist."
I do hope that the new torrent protocol will help with that, especially for "compilations of stuff" (e.g series, episodes, starring XYZ, ...): as I understand it, seeding will become a global file-level thing that can cross torrent boundaries. The new trend of seeding and referencing over I2P might help with keeping the old stuff afloat too.