Start with the title or a remembered contributor, the approximate period and the programme’s subject. Older material can appear under an umbrella strand, an alternative title or a separate archive edition, so one vague keyword may not be enough.
Collect the details you remember
A presenter, location, subject or distinctive episode can be more useful than a general genre. If you remember watching a repeat, the date you watched it may be later than the production date. Say which date you mean. Similarly named remakes and later adaptations can dominate search results, so a production year or cast credit helps distinguish the work you want.
Look for the individual programme within a strand
A recurring documentary banner can contain many unrelated films. The archive may use the individual film title rather than the strand’s familiar name. Specials and interviews can also be listed separately from a regular series. Compare the synopsis instead of assuming that every result using the umbrella title describes the same edition.
Understand what an archive result establishes
An extract can survive or be available when the full programme is not. An archive may also preserve a work without offering it for public streaming. A discovered poster, credit or search listing is therefore an identification clue rather than a promise of current access. If an older copy looks different, its original production format or a later restoration can explain some of the difference.