Today I emailed Grant Sanderson, maker of the YouTube channel 3Blue1Brown, about 69 and the search for nice numbers (blog posts, market), and he actually responded! He said this:

"Very interesting, thanks for sharing. Just reading your message, no special insight occurred to me, but it might be worth mulling over.  I'll throw it on the list of possible video topics (no promises, the list grows much faster than my ability to chip away at it!), and give it some better consideration once I'm finished with the current project."

To count for this market, nice numbers do not need to be the primary topic of the video (which must be on the standard 3Blue1Brown YouTube channel), but it should at least include the basics of nice numbers: what a nice number is, that 69 is the only small one, and that (we think) there are many at higher bases.

General policy for my markets: In the rare event of a conflict between my resolution criteria and the agreed-upon common-sense spirit of the market, I may resolve it according to the market's spirit or N/A, probably after discussion.