Enable "One-click mode"
Install and run Freemake MP3 Downloader. In the program, activate "One-click mode". Choose the following parameters: "Optimal parameters", "Convert to MP3", specify the destination folder.
Copy video URL
Go to the music video and copy its link.
Click browser plugin, YouTube download button, or "Paste URL" in Freemake MP3 Downloader and the sound of the video in MP3 format will be downloaded automatically. Download more MP3s in the same way.