FF60.6 ESR x64 - I always used this extension to watch YT videos in Firefox (browser-independent, better volume control). It worked perfectly, 5 stars.
For the new Firefox now it needs some extra steps, but it's nothing too difficult.
The problem, however, is that here CMD.exe for security resons is only allowed to run with admin permissions, so this addon it's KO for me unless it will manage to use other methods :\

I get double entries for browsers. How to remove them?

Install was NOT painless and I'm fairly surprised that you don't get a right-click option. Opening bookmarks requires you to open it in the browser you don't want it opened in to then perform the actions in Open With to open it in the browser you really want it opened in when it could have just been a right-click or defined command like shift-alt-click.

Useful and works well once configured.
A simple executable script to handle the installation might be useful.

BTW, what's up with the latest update? I don't see why the addon would need access to my download history.

Instruction for installation is insufficient, only thanks to user f495dc (not far below) i managed to install this app

i repeat it again here

1. Install Python (Download from link, run file, and then follow install screens)
2. Download the linked .py file and then move it to a special folder or the root of your C:/ drive (I put mine under the python install folder/Lib)
3. Open a Windows Command prompt (Type command or cmd into Start Menu search and select the cmd.exe)
4. Navigate inside the command prompt to the folder where you put the file in #2 (i.e. "cd c:\path_of_file_folder")
5. Run the command given in instructions: "open_with_windows.py install" (You must be in the same folder as the file)
6. Click Test in the extension info screen inside of Firefox. It will tell you immediately if it worked and you can begin finding/adding external programs to launch

this addon is fantastic but with the new version 7.0.1

I did not understand how it works
and what should be done in Step 3 and 4

i have downloaded the file and installed the program but I don't understand the final step

How the extension works when the file is downloaded what should I do ?

thank you in advance