title: Iframes with Rails 5 not working
body: <p>config/application.rb</p>
  
  <pre><code>config.action_dispatch.default_headers.merge!({'X-Frame-Options' =&gt; 'ALLOWALL'})
  </code></pre>
  
  <p>I added this code but the iframes are still blocked.
  I can't see it (even in private mode with Chrome and after restarting the server)</p>
  
  <p>view/videos/show.rb</p>
  
  <pre><code>&lt;iframe width="560" height="315" src="&lt;%= @video.link %&gt;" frameborder="0" allowfullscreen&gt;&lt;/iframe&gt;&lt;/p&gt;
  </code></pre>
  
  <p>The video isn't shown. 
  Do you have any idea ?</p>