new wp query by tag, it's not showing category post related

I think I have explained very bad. I’ll try again

– Post Type: Video
– Custom post “video” with tag”space”
– Parent category: VideoPage (id=4)
– Children categories: A-B-C

I want show for Parent Category and children only custom post type “video” with tag “space”

In my file category.php I called the template:

<?php
	// If is category or subcategory of $cat_id
if (!function_exists('is_category_or_sub')) {
	function is_category_or_sub($cat_id = 4) {
	    foreach (get_the_category() as $cat) {
	    	if ($cat_id == $cat->cat_ID || cat_is_ancestor_of($cat_id, $cat)) return true;
	    }
	    return false;
	}
}
?>

			<?php if (is_category_or_sub(4)) : ?> 

				<?php load_template(TEMPLATEPATH . '/cat_videopagine.php'); ?>

			<?php else : ?>

Then in the file cat_videopagine.php I have this:

<?php

// The Query
$the_query = new WP_Query( 'post_type=video&tag=space' );

// The Loop
while ( $the_query->have_posts() ) : $the_query->the_post();

?>

The Problem is:
Either in parent cat page or all children cat pages all same custom posts “video” with the tag “space”are displayed so I have
Parent: p1-p2-p3-p4-p5-p6
Cat A: p1-p2-p3-p4-p5-p6
Cat B: p1-p2-p3-p4-p5-p6
Cat C:p1-p2-p3-p4-p5-p6

There should be a function that calls the category and displays only the posts that belong to those category.
Cat A : p1(catA)
Cat B: p3(catB)