How to access form states inside an ajax callback function - ajax

Question

I'm working on a block module and would like to perform ajax operations on its configuration forms when a file is uploaded via a managed_file field.
So when the managed_file hidden field change (once the file is successfully uploaded), there is an ajax callback. The ajax is called like this:
function updateVideo($action){
(function ($) {
$.ajax({
url: '/block_video/update_video', // drupal menu path
dataType: 'json',
type: 'POST',
data: { 'action' : $action },
success: function(data){
// # TODO
}
});
})(jQuery);
}
The drupal path registered above (/block_video/update_video) call a function where I would like to retrieve the block configuration $form_state variable with its current state (not initial). Is it possible to see the current block configuration form states without using javascript directly and without a calling a page refresh?
It would be way simpler for me to just use the '#ajax' property on the managed_file, but it doesn't have it. So I added the ajax callback above by waiting for a value change on the managed_file hidden element and this part is working (using the method described here http://forum.jquery.com/topic/adding-a-change-event-on-a-hidden-field).
I should be able to retrieve the $form_state in my custom ajax callback. I would like to do it the way it's done with the FAPI [#ajax][callback] (both $form & $form_state are passed to the callback parameters - I only need the current $form_state passed to my callback or accessed in it), I couldn't figure how it's done by Drupal.

Answer 1

Alright, I fixed it soon after asking it so here the answer :
I didn't find any solution to retrieve form_states outside the #ajax callback, so when the hidden field state change, I get the current form state directly from a pure jQuery ajax function.
Off topic but kind of related : I managed others form_states inside the usual FAPI #ajax php callback, I needed to call some custom js right after, so with the method below you can trigger a second ajax callback or just a function. It's done this way :
// Code inside the FAPI #ajax callback :
// Trigger the function $.fn.ajaxTrigger defined in my js file.
$commands[] = ajax_command_invoke(NULL, 'ajaxTrigger');
return array(
'#type' => 'ajax',
'#commands' => $commands,
);
With this command you can call any javascript function from a Drupal 7 #ajax callback.