YouTube or Firefox started showing the Windows 10 media pop-up. How can you get rid of it?

As of Sep. 23-24, 2020, either Firefox or YouTube suddenly started spamming the Windows 10 media volume control pop-up, which takes up half the screen. Since I am on my work laptop, just to be on the safe side, I'll point to a YouTube video from earlier this year that addresses this with Chrome:

FIX!!! How To Dismiss Windows 10 Media Volume Control Pop up for Google Chrome

The tiny little volume level bar is perfectly okay; it's the other pop-up beside it, which takes half the screen, that is extremely annoying. How do you get rid of this anti-user deterrent, when you're on Firefox and YouTube (not Chrome or Edge)?

1 Answer

1. Type about:config on the address bar.
2. Click "Accept the Risk and Continue", optionally click Show All.
3. On the search box, type media.hardwaremediakeys.enabled, set it to false. Restart Firefox.

The popup will no longer be shown. Done on Firefox version 81.0 (64-bit).