title: Using custom tags with HTMLPurifier
body: <p>I want to use  and  tags as well as some custom tags (for example , ) with HTMLPurifier. I used </p>
  
  <pre><code>$config-&gt;set('HTML.Allowed','audio, video');
  </code></pre>
  
  <p>to add those tags but received warning that they are not standard and the tags are stripped out.</p>