It does exactly what I want, which is mark videos that I've already seen as watched. Since I follow a fair amount of channels, it's useful to keep track since I can't always remember.

Exactly what I was looking for. All videos are marked.

Hi! Pleasse make the "opacity" slider or the "background-color" option for /* yourect watched fadeout */

Simple and working!

If one day, you could add a list of all watched videos, would be even more great.

simple and elegant and works, what more could you want?

great and superb

it does what its supposed to .
what more to say ?
youtube is garbage and this addon is covering the smell and making it bearable

tnx!

been searching for fix of this youtube issue for a while, this addon seems to do the trick

Fixed my problem with default youtube not marking my videos as Watched.

Scoured the net searching for this particular thing. This is the best among others that offer the same features. I hope it will continue to be updated. Thanks dev.