Use a separate file to record already downloaded URLs

youtube-dl --download-archive archive.txt "https://www.youtube.com/watch?v=toVfvRhWbj8" 

Read URLs from a file (one URL per line)

youtube-dl -a links.txt

Extract audio from a video (and convert it to mp3)

youtube-dl --format 'bestaudio/best' --audio-format 'mp3' "https://www.youtube.com/watch?v=jVfDUvjvUSM"

Download a video and convert it to mp4

youtube-dl --format 'bestvideo+bestaudio/best' --recode-video 'mp4' "https://www.youtube.com/watch?v=Jv8KRwF1zQs"

Have fun and be responsible 🤺