How do I set the default playback rate for all videos, permanently?

Hi, I apologize if I put this in the wrong category. There’s a lot of categories, I searched for an appropriate category but couldn’t really find one. I tried to submit this to Reddit but reddit’s anti-spam policies are too strict and I can never post anything, even after using different accounts.

I watch all media at 2x speed or more. I know some people cannot understand this. I’ve been doing this for years and I cannot imagine not doing it. I’ve learned to understand voices at a much higher speed, and ultimately, I get things done significantly faster. With that out of the way, how do I set the default video playback speed of all videos, permanently?

I do NOT want to use an extension. I’m security and privacy-conscious (same reason why I use firefox), and installing more addons is not something I want to do because it introduces vulnerabilities in the browser. I’m a minimalist, so no addons, especially considering you should be able to achieve this without an addon, and addons just modify stuff you can do yourself anyway. And many of the addons that do this only do it for Youtube, and there are other limitations like they won’t go above 2x. This is not something I’m going to do so please do not suggest it. I would consider creating my own extension, but I don’t know how much knowledge I’d need to be able to create one.

I already know how to change the playback rate of the current tab. At the moment, the way I do it is using the console tab of the dev tools, and I parse the following command:


This works for the current tab, but does not reflect across all tabs nor is it permanent. Side note: I wish there was an easier way to do this (again, NO addons). Yes, there is sometimes an option to select the speed from mp4 videos, but not only is that hit or miss because not every video is mp4, but I also have to change it every single time. I want a more reliable method, and also more granular control over the speed, because the UI only allows you to set it to a maximum of 2.0 and it only has a few predetermined options.

I have tried the following about:config changes but none of them work (after restarting):

Any ideas? Once again, I will not be installing an extension, but I may consider making one myself if it isn’t too much work.