Similarly, maybe only a few people have access to
Star-Gate episode #23. But
if they say that in that episode Cmdr. Pickett gets eaten by a Florgbernian
Rumpox, then I'm willing to ASSUME GOOD FAITH.
In which case, your source isn't the episode, it's those few people
that watched the episode. The episode is reliable, those few people
are not. Therefore, you do not have a reliable source.