Video is moving images and audio. Here are some articles about adding music to your video projects.
2020 - How to add any music track to iMovie on your iPhone Touch Technology Review answers DRM questions, included soundtracks and screen recording from streaming service.
2018 - How to add royalty-free music to iMovie for iOS with iCloud Drive - iMore
2023 - Explore YouTube Studio - Music Library
2014 - Is iMovie Music Copyright Free?
Current - iMovie for iOS in Apple Community with Search
Current - iMovie resources at Apple