Youtube Api获取带视频ID的视频说明

I am trying to get discriptiobn from youtube using api .... but i dont no where am i wrong its not getting for single video . but if i try playlist its working fine, not with video id

Here is my code

error_reporting(E_ALL);

$feedURL = 'https://gdata.youtube.com/feeds/api/playlists/'.$id.'?v=2&prettyprint=true';
$sxml    = simplexml_load_file($feedURL);

echo $feedURL.'</br>';
foreach ($sxml->entry as $entry) 
{       
    echo $media->group->description;
}

Above code is working with playlist ... but if i try one video its not working:

error_reporting(E_ALL);

$feedURL = 'http://gdata.youtube.com/feeds/api/videos/'.$id.'?v=2&alt=json&prettyprint=true';
$sxml    = simplexml_load_file($feedURL);

echo $feedURL.'</br>';
foreach ($sxml->entry as $entry) 
{           
    echo $media->group->description;
}

If you call YouTube api with 'alt=json' parameter, the response will be formatted as JSON not XML. So you should use:

$response = json_decode(file_get_contents('... API URL ...'), true);

And then 'description' can be accessed with:

$response['entry']['media$group']['media$description']['$t']