Well, people who are experiencing difficulties can use my method,
open showthread.php and search for this code
Code:
<vb:if condition="!is_browser('ie') AND $show['wysiwyg']">
<!-- Mozilla work around for focusing on QR in WYSIWYG mode -->
<div id="qr_scroll"></div>
</vb:if>
</form>
Add this below it and save.
Code:
<div class="fb-comments" data-href="http://www.helpline3d.com/showthread.php?t={vb:raw threadid}" data-num-posts="5" data-width="960"></div>
change helpline3d.com to your domain