function video_image($url){
$image_url = parse_url($url);
if($image_url['host'] == 'www.youtube.com' ||
$image_url['host'] == 'youtube.com'){
$array = explode("&", $image_url['query']);
return "http://img.youtube.com/vi/".substr($array[0], 2)."/0.jpg";
}else if($image_url['host'] == 'www.youtu.be' ||
$image_url['host'] == 'youtu.be'){
$array = explode("/", $image_url['path']);
return "http://img.youtube.com/vi/".$array[1]."/0.jpg";
}else if($image_url['host'] == 'www.vimeo.com' ||
$image_url['host'] == 'vimeo.com'){
$hash = unserialize(file_get_contents("http://vimeo.com/api/v2/video/".
substr($image_url['path'], 1).".php"));
return $hash[0]["thumbnail_medium"];
}
}
<img src="<?php echo video_image('youtube URL'); ?>" />