Kama uko na ubuntu use youtube-dl kwa terminal . I have a ultra small pc (uses 25 watts max) with intel atom ,2gb ram and 1TB hard drive for all downloads. I queue the downloads .
To download a video as mp3 file, you can use one of the following commands:
youtube-dl -x --audio-format mp3 https://link to video
If you want to have a cover art for the mp3 file, you can add the --embed-thumbnail option:
In that case the command will look like this:
youtube-dl -x --embed-thumbnail --audio-format mp3 https://link to video
Check more tricks hapa How to Download Songs from a YouTube Video Using YTP-DL