This app is a third party app that is supported by the YouTube API. All content is provided by the YouTube service, the App does not have direct control over the displayed content.
In order to comply with the YouTube Terms of Service,
Does not provide video download function (not music downloader), which means it doesn't save video or offline playback support.
Do not play music in the background,
Do not play music when the screen is off or when the screen is locked.