$term = get_queried_object();

the_widget( 'Streamtube_Core_Widget_Posts', array(
    'post_type'         =>  'video',
    'post_status'       =>  'publish',
    'posts_per_page'    =>  3,
    'orderby'           =>  'post_view',
    'tax_query'         =>  array(
        array(
            'taxonomy'  =>  $term->taxonomy,
            'field'     =>  'term_id',
            'terms'     =>  array( $term->parent )
        )
    )
) );