youtube-dl will output in the current directory
youtube-dl --list-formats URL
youtube-dl -citw ytuser:<USER>
or
youtube-dl -citw URL
youtube-dl -citw <PLAYLIST URL>
youtube-dl -x --audio-format mp3 --audio-quality 320K <VIDEO_URL>
youtube-dl -citw -f 'bestvideo[ext=mp4]+bestaudio[ext=m4a]' <VIDEO_URL>
youtube-dl --cookie "path/to/cookie.txt" <VIDEO_URL>
youtube-dl --list-formats
then
youtube-dl -f <format number> <url>
Download audio and English subtitle
youtube-dl -f 'bestaudio[ext=m4a]' --write-sub --sub-lang en <VIDEO_URL>