yt-untrack by Eduardo

yt-untrack lets you watch YouTube videos while staying fully signed in (Premium, no ads, downloads intact) without those videos being recorded to your watch history or influencing your recommendations.

It works per container: mark any Firefox container as "untracked" in the toolbar popup, then open a video in a tab in that container. The extension cancels YouTube's watch-tracking requests (youtube.com/api/stats/*) only for tabs in the containers you've chosen, so the "I watched this" signal never reaches YouTube's servers. Tabs in every other container behave normally and record as usual.

A red dot on the toolbar icon shows when the current tab is in an untracked container, so you always know whether the video you're watching is being recorded.

No data is collected or sent anywhere. The extension only blocks requests locally in your browser.