While it does work, I found it is being blocked by Facebook for many things, or breaks facebook (firefox). I couldn't see the timeline stream past the visible screen rendered (no scrolling, just grey rectangles forever loading) and chats... this is strange... CTRL+V a link, image data (screen cap to paste) instantly closed the chat window in facebook.com 's messenger pop up window area.

So if you have a use for this keep using it, sure, but facebook is either blocking it or this is blocking facebook. So, use chrome etc for facebook. vice versa. :)

12-02-2022
So in firefox there is an add-on named:
Absolute Enable Right Click & Copy (Force Enable Right Click & Copy) v 1.3.8 updated May 25, 2021

Facebook blocks this and in the opposite direction it messes up pasting screen captures to people in Win10 Win11.
So if you press WIN SHIFT S and copy an area of your screen, usually you can go into messenger
and CTRL + V to paste that from memory into chat.

When this add-on is running (12-04-2022) it breaks that now with either a facebook javascript change on their side, or a firefox change, maybe a change with the add-on. Turn off the add-on and then reload facebook on the browser, and it will allow you to paste screen capture images you don't have to waste the additional step of saving as a jpg or png to your pc first.