Well, the device manufacturers figured that this is the desired behavior for the majority of users, and it wouldn't be worth the trouble to add new settings for the feature. Therefore, only an app can let you record while music plays - Mideo is that app. Below, I'll explain how you can use Mideo for various purposes, like how to record the music while music plays or how to play music while recording a video, whether you're a dancer, weightlifter, drummer, or singer check out some user reviews below. Ok, this does exactly what it says, but here is what earns it the 5 stars. I messaged the dev, Will Said, and his response was quick and to the point. Part of what makes an app great is how well the developer listens AND responds. Take care and enjoy. I hope my review is helpful.
How to move your music from Google Play Music to YouTube Music
How to Play Music While Recording a Video
Learn more here. With a YouTube Music Premium membership, you can choose whether to listen to your music or enjoy the music video experience with a YouTube Music Premium membership. In song mode, you can listen to the music without loading a video. This allows you to continuously enjoy music from your favorite artists, even if you're experiencing low connectivity or video playback issues. In video mode, the music video will play whenever one is available - allowing you to enjoy a complete listening and viewing experience.
Turn on song-only mode:
A new music streaming service from YouTube This is a completely reimagined music service with official releases from your favorite artists. Just search the lyrics or describe it. If you subscribe via iTunes: Payment will be charged to iTunes Account at confirmation of purchase.