Old thumbnails not being deleted. And thumbnails are not deleted from files table.

I fixed both issues. It may not be pretty, but I needed it to work now.
In video.module:
For the deleting of the old thumbnail in function video_upload_manual_thumb(&$element):

  // Remove old image (if any) & clean up database.
  // $old_thumb = $element['data']['video_thumb']['#value']; // -- this value was always empty
  $old_thumb = $element['#default_value']['data']['video_thumb']; // ++ this contains the file path
  if (!empty($old_thumb)) {
  	
    if (file_delete($old_thumb)) {
      //db_query('DELETE FROM {files} WHERE filepath=%d', $old_thumb); // not looking for an id 
      db_query('DELETE FROM {files} WHERE filepath="%s"', $old_thumb); // looking for file path
    }
  }

For deleting the thumbnails when deleting the video in function video_file_delete($file), Just above video_module_invoke('delete', $file); I added these lines:

$thumbnailFile=$file->data['video_thumb'];
	if (!empty($thumbnailFile)) {
	  db_query('DELETE FROM {files} WHERE filepath="%s"', $thumbnailFile);
	}