404 error when I acess the second page of post-type

For modifying the main query, I think it is best to take advantage of the pre_get_posts action.

When using pre_get_posts the $query variable is passed “by reference” which means we can directly manipulate the $query object with the shortcut functions such as set_query_var. Remove the query code from your taxonomy template, and try the following in your functions.php:

function wpa_66609( $query ) {
    if ( is_tax('clipuri') && is_main_query() ) {
        set_query_var( 'post_type', array('post','clip' ) );
    }
}
add_action( 'pre_get_posts', 'wpa_66609' );

If that doesn’t work, I’ll try to debug it.