attachments with tags and get_posts

From this page in the codex, i see that this parameter requires an array so i’d try this way:

$vidArgs = array(
                            'tag__in' => array(5),
                            'post_type' => 'attachment',
                            'post_parent' => $post->ID,
                            'post_mime_type'=>'video/quicktime',
                            'posts_per_page'=>20
                        );

$videos = get_posts($vidArgs);

foreach ($videos as $vid) { ///....