如何使用自定义帖子类型的类别？

Question

我创建了一个“视频”自定义帖子类型。

add_action( 'init', 'create_video_postype' );

function create_video_postype() {     
$labels = array(
    'name' => _x('Videos', 'post type general name'),
    'singular_name' => _x('Video', 'post type singular name'),
    'add_new' => _x('Add New', 'video'),
    'add_new_item' => __('Add New Video'),
    'edit_item' => __('Edit Video'),
    'new_item' => __('New Video'),
    'view_item' => __('View Video'),
    'search_items' => __('Search Video'),
    'not_found' =>  __('No Video found'),
    'not_found_in_trash' => __('No Video found in Trash'),
    'parent_item_colon' => '',
);

$args = array(
    'label' => __('Videos'),
    'labels' => $labels,
    'public' => true,
    'can_export' => true,
    'show_ui' => true,
    '_builtin' => false,
    'capability_type' => 'post',
    'rewrite' => array( "slug" => 'video' ),
    'query_var' => true,
    'menu_icon' => '',  
    'hierarchical' => true,    
    'supports'=> array('title', 'thumbnail', 'excerpt', 'editor', 'page-attributes') ,
    'show_in_nav_menus' => true ,
    'taxonomies' => array('category')

);

register_post_type( 'video', $args);

}

我需要获取“视频”帖子中使用的所有类别。当我使用此函数get_categories（）时，它返回post使用的所有类别。