ass-gist-as-iframe.php

<?php
  /**
   * If you have already included Gist as a handler, you could
   * use this Snippet to include the raw output as iframe...
   * ... if... well if github would permit it... but
   * just for demonstration purposes.
   * **/
   
	add_filter( 'embed_handler_html', 'fwe_embed_handler_html', 10, 4 );
	function fwe_embed_handler_html( $html, $url, $attr, $post_ID = null ){
		if( ! preg_match( '/https:\/\/gist\.github\.com\/(.*)\/(.*)\/?/i', $url, $matches ) )
			return $html;

		return '<iframe src="https://gist.githubusercontent.com/' . $matches[1] . '/' . $matches[2] . '/raw/"></iframe>';
	}
	?>