I'm using one that just decapitalizes and uses a random frame thumbnail from the middle, which is okay.
"DeArrow is an open source browser extension for crowdsourcing better titles and thumbnails on YouTube. The goal is to make titles accurate and reduce sensationalism. No more arrows, ridiculous faces, and no more clickbait.
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There are currently 64,634 users who have submitted 230,432 titles and 107,027 thumbnails."
For those that haven't watched the demo video: for videos that don't have community thumbnails or titles it has options allowing it to automatically pick a random (non-sponsor segment) screenshot and automatically clean up the title (remove emoji, fix capitalization).
Its also very helpfull for determining the quality of the video itself. Usually from that one picture I can tell that even if the video is about a topic I'd like to know more about, I definetly dont want to learn in that specific video. Removing this signal made me waste way more time in videos that seemed good from the tittle alone.
SponsorBlock is significantly more useful but you still see the same kind of annoying people there too. There's a channel called "11foot8" that puts out videos of the local 11'8" (+ 8" after they raised it semi-recently) where trucks disobey the height warning and get destroyed. Most of the videos are around 1 minute long yet there are people picking "highlight" moments in SponsorBlock to skip to the relevant portion. These are mostly videos about a minute long so it baffles me the kind of people whose attention span is that short to want to skip 10 whole seconds to get to the "action". These are the kind of annoying people that rule DeArrow. I didn't want to deal with that anymore