You can use the OpenWith extensions to add it as a right click option.

I have this setup for my non-technical family members, so they just right click on the page choose open with -> ytdlp and it saves it to their downloads folder.

You can set up different options for example video or audio only.

• In Firefox install: https://webextension.org/listing/external-application-button.html
• In the Extension options, add an application
• Name it something like “Open in YT-DLP: mp4”
• Set the exe name to the path of a local copy of yt-dlp
• Set the arguments to be -S res,ext:mp4:m4a --recode mp4 [HREF]
• Under the Placement options -> Context Menu -> select “All Contexts”

You should now be able to right click on a YouTube page and choose “External Application launcher -> Open in YT-DLP: mp4”

If you want audio only, add another application in the extension settings and use the arguments -f ba[ext=m4a] [HREF] for m4a files.