问youtube zend api:结果少于n分钟

EN

$yt = new Zend_Gdata_YouTube();
$yt->setMajorProtocolVersion(2);
$query = $yt->newVideoQuery();
$query->setOrderBy('relevance');
$query->setSafeSearch('none');
$query->setVideoQuery($searchTerms);

// Note that we need to pass the version number to the query URL function
// to ensure backward compatibility with version 1 of the API.
$videoFeed = $yt->getVideoFeed($query->getQueryUrl(2));

$query->setDuration('short');