Given a url of a video hosted on ted, youtube or vimeo, finds where the video is hosted and outputs the thumbnail for that video.

videoThumbnail.php

<?php
    
    function outputVideoThumbnail($url){
        $parsed_url = parse_url($url);	
        
        // if youtube is detected 
        if($parsed_url['host']=='www.youtube.com') { 
            $query 	= $parsed_url['query'];
            $Arr = explode('v=',$query);
            $videoIDwithString = $Arr[1];
        $videoID = substr($videoIDwithString,0,11); ?>
        <img src="http://img.youtube.com/vi/<?php echo $videoID; ?>/mqdefault.jpg"> <?php }
        
        // if vimeo is detected 
        elseif($parsed_url['host']=='vimeo.com') {
            $path = $parsed_url['path'];
            $ArrV = explode('://vimeo.com/',$path); // from ID to end of the string
            $videoID = substr($ArrV[0],1,8); // to get video ID , always length is 8 characters
            $vimdeoIDInt = intval($videoID); // ID must be integer							
            $api_url = 'http://vimeo.com/api/v2/video/' . $videoID . '.php';
            $hash = unserialize(@file_get_contents('http://vimeo.com/api/v2/video/' . $api_url . '.php'));
            $thumbnail = $hash[0]['thumbnail_large'];

            if($thumbnail)
                echo '<img src="' . $thumbnail . '">';
            else							
                echo 'no thumbnail'; 
        }
        
        //if ted
        elseif($parsed_url['host'] = 'ted.com') {
            $end = end(explode('/', $url));
            $request = "http://www.ted.com/talks/oembed.json?url=http%3A%2F%2Fwww.ted.com%2Ftalks%2F" . $end;
            $response = wp_remote_get( $request );
            if( is_wp_error( $response ) ) {
                $result = $this->construct_info_retrieval_error( $request, $response );
                } else {
                $result = json_decode( $response['body'] );
                $result = str_replace( '240x180.jpg', '480x360.jpg', $result->thumbnail_url );
            }
            
            $results = '<img src="' . $result . '">';
            echo $results;
        }
        
        else { echo 'Not youtube, ted or vimeo';}
}
	
?>