First download and install VLC Player
Click on the Media option in the Menu bar and select “Convert/ Save…” option
Under File options, click Add to choose the video file you want to convert. Then click on Convert /Save Option.
In Convert window option and you would get a window that lets you specify the format and the location to save the video.
Click Start to start this converting process. Now you can save a Music Video as a MP3 file on your PC.