MediaInspector Pro by Jeetbuzz

MediaInspector Pro Firefox addon simplifies tracking playlist and subtitle URLs across Apple HLS, Adobe HDS, MPEG-DASH, and Microsoft Smooth Streaming protocols. It facilitates direct video/audio file downloads and monitoring of additional file extensions and Content-Type headers.

Additional options:

Instant URL copying via filename clicks in the addon's popup menu.
Customization options in the options page for direct media file downloads.