protected function _getUploadInfoString() {
        $maxFileSize = $this->getUploadMaxFilesize();
        $allowedExtensions = $this->getAllowedExtensions();
        $lastExtension = array_pop($allowedExtensions);

        $translator = $this->getTranslator();
        $uploadInfoStr = $translator->translate('Only %1$s and %2$s files with a maximum of %3$s MB are allowed');
        $uploadInfoStr = sprintf($uploadInfoStr, implode(', ', $allowedExtensions), $lastExtension, $maxFileSize);

        return $uploadInfoStr;
    }