Bring back the WATCHED overlay to the videos you have already watched on youtube.
< Return WATCHED badge on Youtube (with custom text) 피드백
This has already been discussed. It's how YouTube serves the related videos (videos on the right side of the watch page).
There's nothing I can do as those don't have any indicator that they are watched.
Read more here.
I also have a note on the install page.
I'm sorry but there's nothing I can do to fix that with css alone.
Like I said, the issue you reported is not from this css script, Youtube had broken it and now it seems to finally be fixed after a year.
I'd appreciate if you update your review rating. Thank you.
it is not working at all, half of these already watched.