diff --git a/wp-includes/js/wp-custom-header.js b/wp-includes/js/wp-custom-header.js
index 80e00e5a74..80ebd917dc 100644
--- a/wp-includes/js/wp-custom-header.js
+++ b/wp-includes/js/wp-custom-header.js
@@ -1,5 +1,10 @@
 (function( window, $, settings ) {
 
+	if ( ! ( 'addEventListener' in window ) ) {
+		// Fail gracefully in unsupported browsers.
+		return;
+	}
+
 	function wpCustomHeader() {
 		var handlers = {
 			nativeVideo: {
diff --git a/wp-includes/js/wp-custom-header.min.js b/wp-includes/js/wp-custom-header.min.js
index 7d95db10b1..751f1aff77 100644
--- a/wp-includes/js/wp-custom-header.min.js
+++ b/wp-includes/js/wp-custom-header.min.js
@@ -1 +1 @@
-!function(a,b,c){function d(){function d(){if(c.container=document.getElementById("wp-custom-header"),g()){for(var a in h){var d=h[a];if(h.hasOwnProperty(a)&&d.test(c)){d.callback(c);break}}b("body").trigger("wp-custom-header-video-loaded")}}function g(){return!(a.innerWidth<c.minWidth||a.innerHeight<c.minHeight)}var h={nativeVideo:{test:function(a){var b=document.createElement("video");return b.canPlayType(a.mimeType)},callback:e},youtube:{test:function(a){return"video/x-youtube"===a.mimeType},callback:f}};return{handlers:h,initialize:d,supportsVideo:g}}function e(a){var b=document.createElement("video");b.id="wp-custom-header-video",b.autoplay="autoplay",b.loop="loop",b.muted="muted",b.width=a.width,b.height=a.height,b.addEventListener("click",function(){b.paused?b.play():b.pause()}),a.container.innerHTML="",a.container.appendChild(b),b.src=a.videoUrl}function f(b){function c(){var c=a.YT||{};c.ready(function(){var a=document.createElement("div");a.id="wp-custom-header-video",b.container.innerHTML="",b.container.appendChild(a),new c.Player(a,{height:b.height,width:b.width,videoId:e,events:{onReady:function(a){a.target.mute()},onStateChange:function(a){c.PlayerState.ENDED===a.data&&a.target.playVideo()}},playerVars:{autoplay:1,controls:0,disablekb:1,fs:0,iv_load_policy:3,loop:1,modestbranding:1,playsinline:1,rel:0,showinfo:0}})})}var d=/^.*(?:(?:youtu\.be\/|v\/|vi\/|u\/\w\/|embed\/)|(?:(?:watch)?\?v(?:i)?=|\&v(?:i)?=))([^#\&\?]*).*/,e=b.videoUrl.match(d)[1];if("YT"in a)c();else{var f=document.createElement("script");f.src="https://www.youtube.com/player_api",f.onload=function(){c()},document.getElementsByTagName("head")[0].appendChild(f)}}a.wp=a.wp||{},a.wp.customHeader=new d,document.addEventListener("DOMContentLoaded",a.wp.customHeader.initialize,!1),"customize"in a.wp&&(wp.customize.selectiveRefresh.bind("render-partials-response",function(a){"custom_header_settings"in a&&(c=a.custom_header_settings)}),wp.customize.selectiveRefresh.bind("partial-content-rendered",function(b){"custom_header"===b.partial.id&&a.wp.customHeader.initialize()}))}(window,jQuery,window._wpCustomHeaderSettings||{});
\ No newline at end of file
+!function(a,b,c){function d(){function d(){if(c.container=document.getElementById("wp-custom-header"),g()){for(var a in h){var d=h[a];if(h.hasOwnProperty(a)&&d.test(c)){d.callback(c);break}}b("body").trigger("wp-custom-header-video-loaded")}}function g(){return!(a.innerWidth<c.minWidth||a.innerHeight<c.minHeight)}var h={nativeVideo:{test:function(a){var b=document.createElement("video");return b.canPlayType(a.mimeType)},callback:e},youtube:{test:function(a){return"video/x-youtube"===a.mimeType},callback:f}};return{handlers:h,initialize:d,supportsVideo:g}}function e(a){var b=document.createElement("video");b.id="wp-custom-header-video",b.autoplay="autoplay",b.loop="loop",b.muted="muted",b.width=a.width,b.height=a.height,b.addEventListener("click",function(){b.paused?b.play():b.pause()}),a.container.innerHTML="",a.container.appendChild(b),b.src=a.videoUrl}function f(b){function c(){var c=a.YT||{};c.ready(function(){var a=document.createElement("div");a.id="wp-custom-header-video",b.container.innerHTML="",b.container.appendChild(a),new c.Player(a,{height:b.height,width:b.width,videoId:e,events:{onReady:function(a){a.target.mute()},onStateChange:function(a){c.PlayerState.ENDED===a.data&&a.target.playVideo()}},playerVars:{autoplay:1,controls:0,disablekb:1,fs:0,iv_load_policy:3,loop:1,modestbranding:1,playsinline:1,rel:0,showinfo:0}})})}var d=/^.*(?:(?:youtu\.be\/|v\/|vi\/|u\/\w\/|embed\/)|(?:(?:watch)?\?v(?:i)?=|\&v(?:i)?=))([^#\&\?]*).*/,e=b.videoUrl.match(d)[1];if("YT"in a)c();else{var f=document.createElement("script");f.src="https://www.youtube.com/player_api",f.onload=function(){c()},document.getElementsByTagName("head")[0].appendChild(f)}}"addEventListener"in a&&(a.wp=a.wp||{},a.wp.customHeader=new d,document.addEventListener("DOMContentLoaded",a.wp.customHeader.initialize,!1),"customize"in a.wp&&(wp.customize.selectiveRefresh.bind("render-partials-response",function(a){"custom_header_settings"in a&&(c=a.custom_header_settings)}),wp.customize.selectiveRefresh.bind("partial-content-rendered",function(b){"custom_header"===b.partial.id&&a.wp.customHeader.initialize()})))}(window,jQuery,window._wpCustomHeaderSettings||{});
\ No newline at end of file
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 8a69c4890e..dc1d6e6f8b 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.7-beta1-39049';
+$wp_version = '4.7-beta1-39050';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.