Any browser cookie experts?

Scorpion Ghost

Mar 22, 2013
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I have the weirdest situation.

I use a Firefox extension that changes the user agent on a browser and makes it mobile, and this way Youtube videos play in mobile format. Both on the Youtube website and on embedded Youtube videos this happens. Since a few days ago it stopped working on embedded videos. The embedded video loads, and when I click to play it nothing happens.

I have multiple browsers, and by accident now I found a browser that would play the embedded Youtube videos in mobile format. I tried multiple other browsers with the exact same extensions and everything, and none works.

Then I went to cookies and found a cookie in the working browser ( PREF). Only the browser where it worked had this cookie.

So I figured I copy this one cookie into another browser and see what happens. Unfortunately it seems Firefox doesn't store cookies individually, but all cookies together in a big file. So anyway I copied these files from the working browser to a browser that doesn't work:


And then the browser where I copied the files over after I restarted it the embedded Youtube videos worked.

This cookie is set to expire in September 2023. So 2 years from now. My browsers are set to accept cookies and keep them until they expire. Of course there's no guarantees the cookie will continue working for 2 years, but it works now.

So I'm confused. How can a cookie make such a big difference. And never mind the reason, how can I get that exact cookie and import it elsewhere? I can't be importing all the cookies from a browser to another browser as it changes all the websites you're logged into etc.

I don't know. Can anyone shed some light?