使用OAuth 2.0更新youtube播放列表privacyStatus

I try to update private playlist status on public status but response is not successful, someone know where is the problem?

$listResponse = $youtube->playlists->listPlaylists('status,snippet', array('id' => 'playlist id here'));
$video = $listResponse[0];
$videoStatus = $video['status'];
$videoStatus->privacyStatus = 'public';
$video->setStatus($videoStatus);
$updateResponse = $youtube->playlists->update('status,snippet', $video);

echo '<pre>';
print_r($updateResponse);
echo '</pre>';