Greasy Fork

Love the script.
It's missing one thing though. Import of watched videos from the /feed/history page. Now if I watch video on one PC, the script on other PC doesn't know that, even though the video is marked on my history feed.

As mentioned in the script description, YouTube history data can be imported from other browser/PC, and merged into this script's history in another browser/PC.

yes... but I can't do that everyday on my work and home PC

1. Copy text from the storage tab.
2. Create a file called MarkWatchedYoutubeVideos.txt and paste.
3. Upload it to your personal Google Drive from your work PC.
4. Download the file to your home PC.
5. Copy the text and paste in the storage tab on your home PC.

and do that twice manually every work day. No thanks.
Well. Nothing I can do about it.