Index: src/wp-includes/theme.php
===================================================================
--- src/wp-includes/theme.php	(revision 39914)
+++ src/wp-includes/theme.php	(working copy)
@@ -1322,7 +1322,16 @@
  * @return bool Whether a header video is set or not.
  */
 function has_header_video() {
-	return (bool) get_header_video_url();
+	$has_header_video = (bool) get_header_video_url();
+
+	/**
+	 * Modify whether a header video is set or not.
+	 *
+	 * @since 4.7.2
+	 *
+	 * @param bool $has_header_video Whether a header video is set or not.
+	 */
+	return apply_filters( 'has_header_video', $has_header_video );
 }
 
 /**