Hello @lactas,
You can download 6.5.5 from your apex dashboard.
Here’s a guide on to update. You can try manual update. Although, it is recommended to stay on latest version.
Regarding search result issue, it is a known bug and a fix will be available on upcoming release. Please try adding this custom code on your child theme functions.php as temporary workaround:
add_filter('cornerstone_enable_search', 'disable_search_for_admin');
function disable_search_for_admin ( $enable ) {
return is_admin() ? false : $enable;
}
For the video issue, please share the url so we can check further. Thank you.