Get the Youtube Video Thumbnail from Youtube video Url using PHP

To extract the identifier from the following URL :

$url = 'www.youtube.com/watch?v=B4CRkpBGQzU&feature=youtube_gdata&par1=1&par2=2';

You can first use parse_url() to get the query string :

$queryString = parse_url($url, PHP_URL_QUERY);
var_dump($queryString);

Which, here, would give you :

string 'v=B4CRkpBGQzU&feature=youtube_gdata&par1=1&par2=2' (length=49)

And, then, use parse_str() to extract the parameters from that query string :

parse_str($queryString, $params);
var_dump($params);

Which would get you the following array :

array
  'v' => string 'B4CRkpBGQzU' (length=11)
  'feature' => string 'youtube_gdata' (length=13)
  'par1' => string '1' (length=1)
  'par2' => string '2' (length=1)

And, now, it's just a matter of using the v item from that array, injecting it into the thumbnail URL :

if (isset($params['v'])) {
    echo "i3.ytimg.com/vi/{$params['v']}/default.jpg";
}

Which gives :

i3.ytimg.com/vi/B4CRkpBGQzU/default.jpg

<?php
        function getYoutubeImage($e){
        //GET THE URL
        $url = $e;

        $queryString = parse_url($url, PHP_URL_QUERY);

        parse_str($queryString, $params);

        $v = $params['v'];  
        //DISPLAY THE IMAGE
        if(strlen($v)>0){
            echo "<img src='http://i3.ytimg.com/vi/$v/default.jpg' width='150' />";
        }
    }
?>

<?php
    getYoutubeImage("http://www.youtube.com/watch?v=CXWSlho1mMY&feature=plcp");
?>

$url = "http://youtube.com/watch?v=B4CRkpBGQzU";
$url = explode("&", $url);
$vidID = preg_match("|?v=(.*)|", $url);
$thumb_default = file_get_contents("http://img.youtube.com/vi/$vidID/default.jpg");

$thumb1 = file_get_contents("http://img.youtube.com/vi/$vidID/0.jpg");
$thumb2 = file_get_contents("http://img.youtube.com/vi/$vidID/1.jpg");
$thumb3 = file_get_contents("http://img.youtube.com/vi/$vidID/2.jpg");
$thumb4 = file_get_contents("http://img.youtube.com/vi/$vidID/3.jpg");

Assuming youtube doesn't change their format:

$thumb = preg_match('/watch\?v=(.*)&feature/',$url, $matches);

This will get you the 'B4CRkpBGQzU' part in $matches[1];

Getting the video ID from the URL

$url = "http://www.youtube.com/watch?v=oHg5SJYRHA0&feature=relate";
parse_str( parse_url( $url, PHP_URL_QUERY ) );
echo $vidID;//this is video id

Getting the images

$thumb1 = file_get_contents("http://img.youtube.com/vi/$vidID/0.jpg");
$thumb2 = file_get_contents("http://img.youtube.com/vi/$vidID/1.jpg");
$thumb3 = file_get_contents("http://img.youtube.com/vi/$vidID/2.jpg");
$thumb4 = file_get_contents("http://img.youtube.com/vi/$vidID/3.jpg");