: A vast collection of royalty-free music and sound effects. You can find many tracks under the "Ambient" or "Calm" genres. While the direct download is usually MP3, many video editing tools can help you pair these with visuals to create an MP4.
: Many streaming services like YouTube (with Premium) or Spotify allow you to download content for offline viewing/listening within the app. Download Smooth Meditation Relaxation Sleep Music mp4
: While primarily a mobile app, it is one of the largest libraries of free guided meditations and music tracks. Some content may be available for offline use through their subscription service. How to Save Content as MP4 : A vast collection of royalty-free music and sound effects