Here are simple tutorial links on how to set up MP4 video on iPhone lock screen ( live photo ) and Android home and lock screen!

iPhone tutorial link:
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https://www.youtube.com/watch?v=DoMHgqXV30k



Android tutorial link:
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Samsung Galaxy:
https://www.youtube.com/shorts/O-_hw75QrsU

Other:
Most of Android phone manufactures has an option to set up a video on a lock screen or home screen! Generally it should be very easy to do just like with Samsung Galaxy ( One UI ) phones!