jsfiddle-oembed.php

<?php
wp_embed_register_handler( 'jsfiddle', '#https?://jsfiddle.net/.*#i', 'huypham_embed_handler_jsfiddle' );
function huypham_embed_handler_jsfiddle( $url ){
  global $content_width;
  $url = $url[0];
  $height = '300';
  $width = $content_width?$content_width:'100%';
  $query = parse_url($url,PHP_URL_QUERY);
  $url = trailingslashit(preg_replace('#\?.+#i', '', $url));
  parse_str($query,$query);
  if (isset($query['height'])) {
    $height = $query['height'];
  }
  if (isset($query['width'])) {
    $width = $query['width'];
  }
  if( !preg_match( '#/embedded/#i', $url ) )
    $url .= 'embedded/';
  return '<iframe width="'.$width.'" height="'.$height.'" src="'.$url.'" allowfullscreen="allowfullscreen" frameborder="0"></iframe>';
}