function getVimeoMP4($vimeo_id) {
  $result = file_get_contents( "http://keepvid.com/?url=http%3A%2F%2Fvimeo.com%2F" . $vimeo_id );
  preg_match_all('/"(http\:\/\/pdl.vimeocdn.com.+?)"/i', $result, $matches);
  return $matches[1][1];
}