Great AddOn but it stopped working today.
Here is what happened, maybe someone can help me: today I ran CCleaner and then no more videos were marked.
I tried to reinstall the Addon, I tried to reboot the PC but both didnt work. I then tried to use the History Synchronize button and it says "synchronizing with history" but the progress stays at 0 and the "close"button is greyed out and I cant click it. I am desperate and I dont know what to do anymore :/

edit: ty for the fast response. Problem is fixed!

Great and a"must have" addon for Youtube users.

Feature request:
Add a feature that it removes watched from the https://www.youtube.com/feed/subscriptions when the video is marked as a watched. Give users a options when it removes them (when the video is full watched, 50% watched and so on).

Simple and works like a charm.

Essential for anybody who is really into YouTube.

Not sure it works permanently. Old videos I've watched are not being marked.

I'm looking for an extension that permanently stores YouTube history, and this seems to be a decent but imperfect solution.

TOP!! Works fine!

Thank you for making this addon for firefox. its working so far, this is the firefox version that im using (57.0 - 64bit)

worked very well until i updated to ff 57. totally loved it when it worked.
since updating to 57 my history and database are empty. and sadly no more "watched" videos.
when click on "synchronize" in the history-options a unclickable message saying "synchronizing with history" appears but nothing else happens until i reload or close the tab.
the search wheel at the buttom right is constantly turning but not finding anything.
already tried reinstalling the addon, overinstalling the browser and restarting the mac (os 10.12.6). it's just not working anymore.
on my older mac with el capitan this great addon strangely still works under ff 57.
any ideas?

G

It works great for what I need it to except for 1 minor problem. My subscriptions page just shows a blank white screen when this is enabled. For me to be able to view the videos in my subscriptions the way I want to, I need to disable this addon, click view subscriptions so the videos show up, then click to re-enable the addon so I can easily see which video I've watched.

.Works perfectly in Firefox 61 Beta....

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.

Works well but I wish it had the ability to hide watched videos so that they don't clutter up the subscriptions feed.

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

Update:
(04.01.2020) Add-on still works but I too have recently run into bug? creating double thumbnails. Few people complained about add-on being broken. Actulaly the problem is with youtube's new layout not add-on.
Simple solution for it is adding "f6=8" value (without quotes) to a PREF cookie, r creating PREF cookie with this value if you don't have one already.
That value will change youtube layout to old layout.

Original review:
Add-on itself is very useful as it makes my life much easier.
However, I tend to open several videos at once and then watch them. I have noticed that add-on marks videos as watched the moment I open them in new tab, without actually hitting the play button.
It would make much more sense, for me anyway, if the add-on marked videos as watched after I watched them, not before.