Index: src/wp-content/themes/twentyseventeen/style.css
===================================================================
--- src/wp-content/themes/twentyseventeen/style.css	(revision 40915)
+++ src/wp-content/themes/twentyseventeen/style.css	(working copy)
@@ -1739,7 +1739,6 @@
 @supports ( object-fit: cover ) {
 	.has-header-image .custom-header-media img,
 	.has-header-video .custom-header-media video,
-	.has-header-video .custom-header-media iframe,
 	.has-header-image:not(.twentyseventeen-front-page):not(.home) .custom-header-media img {
 		height: 100%;
 		left: 0;