A simple WebExtension for Firefox to play back media in an external player. Listed on addons.mozilla.org.
play-with was originally intended to use mpv via the youtube-dl hook for a long list of supported sites. However, it will also work with other media players with M3U support, e.g. VLC, for direct media URLs.
If you want to use youtube-dl+mpv on Windows, install a recent mpv build and place the youtube-dl.exe inside the mpv folder as described on this page.
There have been addons on AMO prior to the release of play-with, but they depend on native-messaging. This WebExtension is designed to work on its own, without the need to install native messaging software on the host.
This is achieved by creating a plain text file with the M3U header, paste the current link into it and open the downloaded M3U playlist in your preferred media player.
This project is licensed under the GPL. The used icon is from Mozilla's Photon collection and licensed under the MPL.