Get the URL of a thumbnail for a video on a 3rd-party service

get-video-thumbnail.php

<?php

/**
 * Get the URL of a thumbnail for a video on a 3rd-party service
 *
 * @param       string		$url	Currently supports YouTube and Vimeo
 * @return	string
 */
function pilau_get_video_thumbnail( $url ) {
	$thumb_url = null;
	$service = null;
	$url_parts = parse_url( $url );

	// Which service?
	if ( strpos( $url_parts['host'], 'youtube' ) !== false ) {
		$service = 'youtube';
	} else if ( strpos( $url_parts['host'], 'vimeo' ) !== false ) {
		$service = 'vimeo';
	}

	switch ( $service ) {

		case 'youtube': {
			$qs_parts = explode( '&', $url_parts['query'] );
			foreach ( $qs_parts as $qs_part ) {
				$qs_part = explode( '=', $qs_part );
				if ( $qs_part[0] = 'v' ) {
					$thumb_url = 'http://img.youtube.com/vi/' . $qs_part[1] . '/default.jpg';
				}
			}
			break;
		}

		case 'vimeo': {
			$image = unserialize( file_get_contents( 'http://vimeo.com/api/v2/video/' . $url_parts['query'] . '.php' ) );
			$thumb_url = $image[0]['thumbnail_small'];
			break;
		}

	}

	return $thumb_url;
}