$re = '/<div.*?>\s?(.*?)\s?<\/div>/';
$str = '<div class="thumbnail label_c_hd">HD</div>
<div class="thumbnail label_c">
1 / 3 FOR GROUP
</div>
<div>1 / 3 FOR GROUPS
</div>
';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php