There is / was also r/DeepIntoYoutube which was dedicated to good videos that only had a handful of views.

It reminds me of this grandma that played Skyrim for ages but never had any views, but thanks to one of these discover pages, she got a following of tens of thousands.

And before that it was a neat trick to find obscure images in your favorite search engine. "Index of" is/was also a good keyword to get at file listings.