diff -up wordpress/wp-includes/js/tinymce/plugins/media/plugin.js.orig wordpress/wp-includes/js/tinymce/plugins/media/plugin.js
--- wordpress/wp-includes/js/tinymce/plugins/media/plugin.js.orig	2019-02-21 14:59:28.793415420 +0100
+++ wordpress/wp-includes/js/tinymce/plugins/media/plugin.js	2019-02-21 15:00:14.319647286 +0100
@@ -166,7 +166,6 @@ var media = (function () {
         mp4: 'video/mp4',
         webm: 'video/webm',
         ogg: 'video/ogg',
-        swf: 'application/x-shockwave-flash'
       };
       var fileEnd = url.toLowerCase().split('.').pop();
       var mime = mimes[fileEnd];
@@ -424,14 +423,6 @@ var media = (function () {
       var allowFullscreen = data.allowFullscreen ? ' allowFullscreen="1"' : '';
       return '<iframe src="' + data.source1 + '" width="' + data.width + '" height="' + data.height + '"' + allowFullscreen + '></iframe>';
     };
-    var getFlashHtml = function (data) {
-      var html = '<object data="' + data.source1 + '" width="' + data.width + '" height="' + data.height + '" type="application/x-shockwave-flash">';
-      if (data.poster) {
-        html += '<img src="' + data.poster + '" width="' + data.width + '" height="' + data.height + '" />';
-      }
-      html += '</object>';
-      return html;
-    };
     var getAudioHtml = function (data, audioTemplateCallback) {
       if (audioTemplateCallback) {
         return audioTemplateCallback(data);
@@ -494,8 +485,6 @@ var media = (function () {
         });
         if (data.type === 'iframe') {
           return getIframeHtml(data);
-        } else if (data.source1mime === 'application/x-shockwave-flash') {
-          return getFlashHtml(data);
         } else if (data.source1mime.indexOf('audio') !== -1) {
           return getAudioHtml(data, audioTemplateCallback);
         } else if (data.type === 'script') {