Yesterday, I started watching a video on YouTube but closed out of my browser (Firefox) only a few minutes into the video.

I've got my Firefox set to delete all cookies, history, form data, etc on every close. (Pretty much everything but bookmarks.) The image on this post is a screenshot of my relevant settings.

Today, after having exited my browser and fully shut down my computer for a while, I remembered the video and decided to continue watching it.

In Firefox, I searched for the video (I used the search term "gnu taler" -- something worth looking into especially for folks interested in this particular Lemmy community by the way). In the search results, the video I was searching for showed the red bar at the bottom indicating I'd watched only the first few minutes of it.

Which seems weird given that I'd cleared all my browser data since I watched the first few minutes.

So I did some experimentation. I closed my browser completely again and opened it back up, searched in YouTube, and it still had the indicator. I updated to the latest version of Firefox in the Arch package repository. Same indicator. I tried the same in Chromium (which I've also got set to delete all browser data on close). Still the indicator. I installed Tor Browser Bundle (specifically torbrowser-launcher on Arch Linux), changed none of the default settings at all, and searched in YouTube. The indicator is present. In Tor Browser Bundle.

W

T

F

?

Anybody have any idea how that's possible?

My only guesses are:

• That search is so niche as to be literally unique (which if true makes me sad -- I really hope GNU Taler takes off and becomes widespread) and YouTube is using that to identify me.
• YouTube doesn't know where I left off at all. Not even my browser knows (because if it was my browser keeping track, it wouldn't persist between browsers). It's something else on my system that my browsers depend on or tap into.

The only other pieces of relevant info I can think to share:

• There's another video (also about GNU Taler) that I watched all the way through the same day that I started the video this post is about. It doesn't show any indicator.
• I tried searching on my phone's browser. No indicator. But then I'm not sure my phone ever shows indicators. I haven't tried this on any other devices on my network or anything.
• I still haven't watched the video in question. Heh.

Thanks in advance for any insight you might have.

Edit: Sorry for neglecting to mention previously that at no point during any of the above did I log in to YouTube. And the "Sign in" button was visible at the top of the page indicating I wasn't logged in. Since multiple people asked, I figured I should edit my OP with that info.

Edit2: Two more things to mention. I think some folks are thinking I copied the link and pasted it between browsers during the above test or something? The only reason the timestamp is included in the link I posted above is because when I copied it into this post, I didn't think to remove the timestamp. But I didn't do anything like copying the link from the search results in one browser and then paste the link into TBB or anything. In each separate browser, immediately after opening the browser, I went to YouTube (by typing "youtube.com" into the address bar) and put "gnu taler" into the search bar and hit enter. And in each browser, YouTube somehow remembered where I'd left off in a whole different browser -- with a different IP address in the case of the switch from Chromium to TBB. And no urls were copied between browsers in any of the above.

The other thing to mention. Changing my search term to the full title of the video ("Building an Open Source Payment System - Sebastian Javier Marchano, Taler System" sans quotes) gives the relevant video as the top search result, but no "left off" indicator. And I'm in the Firefox in which I first noticed it had remembered.

Oh, actually, one more thing to mention. After posting this, I continued watching. I'm probably about 3/4 done with it now. But I closed my browser again before completing it, reopened my browser, and searched "gnu taler". It gives the indicator, but the position of the indicator is roughly (possibly exactly) where it was when I first noticed it had remembered. Not where I left off after watching to roughly the 3/4 mark.

Edit3: Wow! Ok. I'm 99% sure folks smarter than me have hit upon what's going on here. Thanks in particular to Tony N and Chozo for the right answer. It looks like YouTube has a feature where, depending on your search terms, it may automatically skip you a certain ways into the video. (Like "oh, you searched for 'gnu taler'? Well, in this video result, this bit in the middle is the part that's relevant to your search terms, so we'll just start you such-and-such-many seconds into the video.") The red bar doesn't mean "you've watched this" at all. And YouTube isn't "remembering me" between browsers. It's just consistently (as long as I use the specific search terms "gnu taler") suggesting that I start that video 273 seconds in rather than from the beginning. And anyone who searches that exact search term should get similar results... unless they're on mobile for some weird reason? That paired with the coincidence that I'm pretty sure I just happened to have stopped the video yesterday right about at the same place where YouTube recommends you start had me very confused. Whatever the case, I'm satisfied this must be the right answer. Thanks again, ya'll!