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.)