Simply put, the button you see right below can help you convert video you're browsing on YouTube to MP3 format in just 1 click. All that's required from you is to drag-and-drop the button to your browser's bookmarks. Then click it while browsing YouTube videos, and you'll see how easy it is to convert any video to MP3 with just 1 click.
Hint: it's best to do this on a desktop or a laptop computer, then sync it into your mobile device. It's a special little button that has our domain with a bit of code attached to it, so it needs to be dragged by mouse and dropped to bookmarks section of your browser to be saved properly. Unless you have some app that enables drag and drop functionality in browser on your smartphone, drag and drop is not something that often works on mobile devices.