I love your concept of "harvesting." So much so that I decided to expand the Q&A for my talk with lots more questions and answers :). Here they are:
https://emacsconf.org/2022/talks/maint/
Btw, I asked about VTT chapter markers on #emacsconf-org but I guess there's no one active on there at the moment:
<countvajhula> I've finished adding NOTEs in the VTT file for the Q&A for my
talk, and I used subed to split the captions where the NOTEs
should be inserted [18:25]
<countvajhula> what should I do now?
<countvajhula> the wiki page mentions "subed-align" and
"emacsconf-subed-make-chapter-file-based-on-comments" but I'm
not quite sure what those do [18:27]