As Felix pointed out (and I had not previously realized), the subtitles depend mostly on the audio, and the video can largely be ignored. I thus think it has relatively little to do with blind.
I had looked at mpv and came upon the annoyingly close but still unhelpful watch-later feature. I considered whether it was possible to implementing my proposal with just edits to input.conf and whether it was worth using libmpv, but had not considered lua scripts. A Lua script indeed looks promising. https://gist.github.com/Hakkin/5489e511bd6c8068a0fc09304c9c5a82 https://github.com/thebombzen/scripts/blob/master/src/markchapter.lua It still seems a bit messy, (Perhaps a scripting language could be avoided entirely if the mpv configuration were written in C.) but this will probably satisfy me for now.
