somebody explain me what this function do

[b2k]

Technically what this do?

 

I know that download videos from youtube, but i need to know exactly how its work

 

if (isset($_GET['url'])){
$url=$_GET['url'];
$url=trim($url);

if (strstr($_GET['url'],"youtube.com")){
	$data = @file_get_contents($_GET['url']);
	@preg_match('#/watch_fullscreen\?video_id=([a-z0-9-_]+)&l=([0-9]+)&t=([a-z0-9-_]+)#i', $data, $matches);
	if (ereg($matches[1], $_GET['url'])) {
		Header("Location: http://www.youtube.com/get_video?video_id=$matches[1]&l=$matches[2]&t=$matches[3]");
	} 
}
}

[taith]

basically, it grabs the file, looks for a url like "#/watch_fullscreen\?" and some letters/numbers/etc after it... and if it finds one, redirects to it...