If you use Youtube to listen to music, you'd be consuming from 114 MB to 1,65 GB per hour, depending on the quality you choose.
A decent choice if you aren't concerned about high quality or low file size.
And, in case you wonder how widespread this format is, just consider it's the standard audio format for Windows PC.
Aside from being able to convert videos for free, you can also edit the output before you save it on your device.
Having the music you like downloaded once rather than continually having to stream it would be a more sensible choice.
Once the app is installed on your Android device, you will be able to search for the desired videos in the Find videos tab.