Thanks, this worked!
We have ended up with this code(I don’t know why is working):
add_filter( 'manage_edit-news_sortable_columns', 'set_custom_news_sortable_columns' );
function set_custom_news_sortable_columns( $columns ) {
$columns['iframe'] = 'iframe';
$columns['video'] = 'video';
return $columns;
}
if( 'video' == $orderby ) {
$query->set('meta_key','video');
$query->set('orderby','meta_value');
$query->set('meta_type','video');
$query->set('ignore_sticky_posts',true);
}