I have the following code in my form.

function video_subtitles_menu() {
    //print "video_subtitles_menu 1";exit;
  $items = array();
  $items['video_subtitles_test/upload'] = array( //this creates a URL that will call this form at "examples/form-example"
    'title' => 'Upload Subtitle', //page title
    'description' => 'Uploading subtitle for videos',
    'page callback' => 'drupal_get_form', //this is the function that will be called when the page is accessed.  for a form, use drupal_get_form
    'page arguments' => array('video_upload_subtitles_form'), //put the name of the form here
    'access callback' => TRUE
  );
      //print "video_subtitles_menu 2";exit;
  return $items;
}

function video_upload_subtitles_form($form, &$form_state) {
 $form = array('#attributes' => array('enctype' => 'multipart/form-data'));
 $form['video_name'] = array(
    '#title' => t('Name Of the video'),
    '#type' => 'textfield',
 );

 $form['sub_file'] = array(
        '#type' => 'file',
        '#title' => t('Upload video'),
        '#size' => 48,
        '#description' => t('Pick a video file to upload.'),
    );
 $form['submit_button'] = array(
    '#type' => 'submit',
    '#value' => t('Submit'),


    );
 return $form;

}

function video_upload_subtitles_form_validate() {
  if(!file_check_upload('upload')) {
    // If you want to require it, you'll want to do it here... something like this:
    form_set_error('upload', 'File missing for upload.');
  }
}

function video_upload_subtitles_form_submit($form, &$form_state) {
 $video_name = $form_state['values']['video_name'];//I am able to get this 
 $file = file_save_upload('sub_file', array());
print "<pre>";print_r($file);// no response here 
drupal_set_message(t('The form has been submitted.'));//this also not printing 
}

On the submission handler, it only returns the text field, I don`t get anything from file upload field, when I use file_save_upload.

This is the response which i get in firebug, I have tried uploading text and excel file.

What I am trying to do is create a block where you can upload a file than I need to get the url to upload it to CDN but how to get the link of file at form submission.

I am using Drupal 7 by the way.