You can download a video as audio mp3 file. Here is one old trick. Add "ss" before youtube i in the link. Follow this one ssyoutube.com/watch?v=YOcmSsBfafg
I tried it. It won't create mp3 file. after you put the youtube url on the link, it downloads an application to be installed. My Sophos detected harmful PUA and now I am trying to clean it up. I would not touch this link anymore
Yes you can add ss before youtube inn the link or just use nice sites where you can captured only audio https://youtube7-mp3.org or that one https://mp3skulls.tube the difference is just with a design
Another great site I want to share with you is Facebook video downloader and converter which help you to download any video and mp3 from facebook content. Here you can find it: http://fb-keepvid.com