YouVideo To MP3 is a useful app for converting your smartphone videos to MP3s, saving just the audio so you can listen to it without having to watch the whole video.
There are three buttons on the main screen. The first is to convert the video; the second is to access audios you've already saved. If you tap on the first button, a tab will open to show you all the videos on your smartphone so you can select the one you want to convert. If you want to convert the video, you can also select its duration and review the result before you save it.
The audio will be renamed and saved in a new folder. You can access these files on the app with the second button on the main screen, from which you can listen to them or share them on other apps.
YouVideo To MP3, like Video To Mp3 Converter and MP3 Video Converter, converts videos to MP3s exactly as it promises.