code: def FILER_STORAGES(self):
          
          if not self.FILER_CUSTOM_NGINX_SERVER:
              return {}
  
          return {
              'public': {
                  'main': {
                      'ENGINE': self.default_file_storage,
                      'OPTIONS': {},
                      'UPLOAD_TO': 'filer.utils.generate_filename.by_date',
                      'UPLOAD_TO_PREFIX': 'filer_public',
                  },
                  'thumbnails': {
                      'ENGINE': self.default_file_storage,
                      'OPTIONS': {},
                      'THUMBNAIL_OPTIONS': {
                          'base_dir': 'filer_public_thumbnails',
                      },
                  },
              },
              'private': {
                  'main': {
                      'ENGINE': 'filer.storage.PrivateFileSystemStorage',
                      'OPTIONS': {
                          'location': self.filer_private_files_path,
                          'base_url': '/smedia/filer_private/',
                      },
                      'UPLOAD_TO': 'filer.utils.generate_filename.by_date',
                      'UPLOAD_TO_PREFIX': '',
                  },
                  'thumbnails': {
                      'ENGINE': 'filer.storage.PrivateFileSystemStorage',
                      'OPTIONS': {
                          'location': self.filer_private_thumbnails_path,
                          'base_url': '/smedia/filer_private_thumbnails/',
                      },
                      'THUMBNAIL_OPTIONS': {},
                  },
              },
          }
docs: Filer config to set custom private media path
          http://django-filer.readthedocs.org/en/0.9.4/settings.html#filer-storages