It’s useful for --mark-watched , you’d populate it with --cookies-from-browser firefox --cookies /tmp/cookies.txt. I managed to get an account banned for doing that, so use with caution.

Used in converting videos to podcast episodes using dir2cast:

--force-ipv6 #use with net.ipv6.conf.all.use_tempaddr = 2
--ffmpeg-location "~/src/FFmpeg" #selfcompiled ffmpeg with he-aac support
#convert to he-aac (v1, for music bed compatibility) and filter mic noise:
--exec "~/src/FFmpeg/ffmpeg -y -i %(filepath)q -af afftdn=nf=-25,highpass=f=100 -c:a libfdk_aac -profile:a aac_he -b:a 64k -ar 44100 -c:v copy -disposition:v attached_pic -map_metadata 0 -map_chapters 0 %(filepath)q.filtered.m4a && mv %(filepath)q.filtered.m4a %(filepath)q" 
--js-runtimes quickjs #for solving challenges
--remote-components ejs:github #for updates on how to solve the challenges
--extract-audio 
--audio-format m4a #best compatibility with dir2cast & overcast
--embed-thumbnail
--embed-metadata
--embed-chapters
--no-progress #this thing runs as a systemd timer service, prevent logspam
--paths /tmp/ytdlp #no unnecessary writes to storage
--sponsorblock-remove default #remove in-video ads
#only download the newest video from a channel at most 1 month old:
--break-on-existing
--break-on-reject
--dateafter now-1month
--download-archive ~/var/downloaded.ytdlp