I've used this one for so many things and it's awesome.

I've downloaded a whole youtube channel, downloaded videos as mp3's and what not.

I have couple of aliases set in my .zshrc too :)

mp3dl() { youtube-dl --extract-audio --audio-format mp3 $1 }

root@haseebr7 ~ mp3dl <youtube_video_url>

and bam i have the mp3 download. I no longer have to visit shitty ad infested websites to do these kind of things.