Source

File: wp-admin/includes/media.php

function media_upload_html_bypass() {
	?>
	<p class="upload-html-bypass hide-if-no-js">
		<?php _e( 'You are using the browser&#8217;s built-in file uploader. The WordPress uploader includes multiple file selection and drag and drop capability. <a href="#">Switch to the multi-file uploader</a>.' ); ?>
	</p>
	<?php
}