Youtube now have millions of free mucis video collection, Sometime you may just want to listen the track, but not interested to watch the videos. Maybe you can download the videos using some 3rd part software and convert that video to mp3 using some other 3rd part track.
Yes its quite understandable this is too much painfull job, isn't it.
Me my my team worked on a new project we names it "tubidy" using our tubidy app we can auto download any youtube video as well as we can convert that to mp3 track, high quality mp3 to low quality mp3 any formate as you need!