Ticket #39512: 39512.2.diff

src/wp-includes/theme.php

@@ -1338 +1338 @@
         $id = absint( get_theme_mod( 'header_video' ) );
         $url = esc_url( get_theme_mod( 'external_header_video' ) );
 
-        if ( ! $id && ! $url ) {
-                return false;
-        }
-
         if ( $id ) {
                 // Get the file URL from the attachment ID.
                 $url = wp_get_attachment_url( $id );
         }
 
+        /**
+         * Modify the header video url.
+         *
+         * @since 4.7.3
+         *
+         * @param string $url Header video url, if available.
+         */
+        $url = apply_filters( 'get_header_video_url', $url );
+
+        if ( ! $id && ! $url ) {
+                return false;
+        }
+
         return esc_url_raw( set_url_scheme( $url ) );
 }