This article explains how to turn a video into wallpaper on your iPhone or Android smartphone. Instructions apply to iPhone 6S and later, and devices running Android 4.1 and later.
How to Set a Video as Your iPhone Lock Screen Wallpaper!
To use a video background on your iPhone, select a video clip you recorded using the Live Photo feature in your iPhone's Camera app.
Go to Settings > Wallpaper.
Select Choose a new background.