In general, YouTube Pro Downloder acts and works exactly like the official YouTube client. In fact, it's an old version of the YouTube client but there's one small difference. The difference is that, under the videos, you'll see a download button. When you tap this download button, you can choose the format and quality you want and download the video to your smartphone in.
With YouTube Pro Downloder, you can also do the same things that you can do with the official YouTube client, like playing videos in the background. But it's very important NOT to log in, because if you log in on this app, you'll lose the download feature. So don't do it.
YouTube Pro Downloder is possibly the best YouTube video downloading tool that you can find on Android - and there are a lot of really good ones! It's easy to use and has an intuitive interface (just like YouTube's) making it the best way to download videos.