gistfile1.txt

<?php 
  		if ( get_post_meta($post->ID, 'video', true) ){
			
				echo '<img src="';
				
				$src = the_field('video');
		 
				preg_match('!video\/([0-9]+)!i', $src, $match);
				 
				$id       = $match[1];
				$apiurl   = 'http://vimeo.com/api/v2/video/' . $id . '.json';
				$response = file_get_contents($apiurl);
				$json     = json_decode($response, true);
				 
				print_r($json[0]['thumbnail_large']);	
				
				echo '">';
			}
		?>