[dootzky]

ja sam imao isti problem (tj. request), i isto sam pitao to na forumu, evo ti link:
http://www.devprotalk.com/showthread...hlight=youtube

na kraju sam to resio klasicnom kradjom
evo ti kod koji sam koristio, u nadi da ce ti dati makar insight u jedno resenje.
*note da je ovo samo za youTube..*

// jel' ovo uopste youtube embeded video?
$parchePos = strpos($nekiEmbededLink, "www.youtube.com/v/");

if ($parchePos === false) {
	// ako nije youTube, postavi neki default.. bla..
}
else {
	$youtubeID = substr($nekiEmbededLink, $parchePos + 18, 11);
	
	// KRADI!! :D
	$ch = curl_init ("http://img.youtube.com/vi/$youtubeID/1.jpg");
	curl_setopt($ch, CURLOPT_HEADER, 0);
	curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
	curl_setopt($ch, CURLOPT_BINARYTRANSFER, 1);
	$rawdata=curl_exec ($ch);
	curl_close ($ch);
	
	$fp = fopen("userPhotos/{$article_id}.jpg", 'w');
	fwrite($fp, $rawdata);
	fclose($fp);
}