WP_Query doesn’t accept Category ID

Question

If your category is custom taxonomy you’ll have to use tax_query in you WP_Query().

See: https://codex.wordpress.org/Class_Reference/WP_Query#Taxonomy_Parameters

I guess it’s a typo that you have &catid instead of $catid.

Edit:
Something like:

$args_query = array(
'posts_per_page' => 6, 
'post_type' => 'video',
    'tax_query' => array(
        array(
            'taxonomy' => $taxonomy,
            'field' => 'term_id',
            'terms' => $catid
        )
     )
);

Note: Check for typos since I have not tried or tested this.