I've looked thru the reviews for this extension to figure out how to install it and none of the suggestions have helps. When I run the cmd line I get the same result every time:
C:\Users\metal321\OpenWithScript>open_with_windows.py install
This is the Open With native helper, version 7.2.6.
Run this script again with the word "install" after the file name to install.

I found this extension: Open in Google Chrome Browser
https://addons.mozilla.org/en-US/firefox/addon/open-in-chrome-browser/#:~:text=%22Open%20in%20Google%20Chrome%22%20extension,manually%20copy%20and%20paste%20links.

It works by simply installing it and there are a number of other
extensions for other browsers and programs listed here:
https://add0n.com/open-in.html?from=chrome&version=0.2.8&type=install

I found the extension great, but I can't install the script.
I type the path in cmd with the script name and then install, but cmd keeps telling me to type install.

C:\Users\User\AppData\Local\Programs\Python\Python310>open_with_windows.py install
This is the Open With native helper, version 7.2.6.
Run this script again with the word "install" after the file name to install.

I have no idea where the error is.

Useful to run commands like mpv or yt-dlp. I've quickly reviewed parts of the source code, looks fine.

For the above commands, best practice is to add "--" as the last argument. (Maybe not a real concern, because the URL is passed as a single argument and probably cannot start with "-", but just in case.)

(Update 2023-12: Keeps working for me, for years, without maintenance.

Intitial setup was a hassle, but it's much easier than when I wrote my own private extension for the same purpose. Firefox keeps deactivating that one all the time, because apparently I shouldn't trust my own code, lol.)