diff -r 34716fd837a4 -r be944660c56a wp/wp-includes/js/wp-custom-header.js
--- a/wp/wp-includes/js/wp-custom-header.js	Tue Dec 15 15:52:01 2020 +0100
+++ b/wp/wp-includes/js/wp-custom-header.js	Wed Sep 21 18:19:35 2022 +0200
@@ -287,9 +287,10 @@
 				video = document.createElement( 'video' );
 
 			video.id = 'wp-custom-header-video';
-			video.autoplay = 'autoplay';
-			video.loop = 'loop';
-			video.muted = 'muted';
+			video.autoplay = true;
+			video.loop = true;
+			video.muted = true;
+			video.playsInline = true;
 			video.width = this.settings.width;
 			video.height = this.settings.height;