Stacher is a great GUI for yt-dlp on Windows and MacOS.

That is a cool option I hadn’t thought of trying.

But they can pull different quality profiles based on your list preferences right? I don’t see why you need one instance for downloading 4k and one for 1080p.

I believe these are “remux” when searching. I don’t think anyone posts an ISO but the remux contains the entire contents of the original disc but in a friendlier format for playback on more diverse hardware (mkv containers for instance instead of the bdmv container).

Can you elaborate on why you’d need two instances of radarr/sonarr running at once?