This is the URL the user would post in XF:
https://www.sporcle.com/framed/?v=8&pm&gid=137614f712d0&fid=5c5323c3d107c&width=580
This would be the actual code substituted:
<iframe frameborder="0" scrolling="no" marginheight="0" marginwidth="0" id="spFrame5c5323c3d107c"
src="https://www.sporcle.com/framed/?v=8&pm&gid=137614f712d0&fid=5c5323c3d107c&width=580" style="width:100%;"></iframe>
<script type="text/javascript" src="https://www.sporcle.com/embed/embed.js?v=5c5323c3d107c"></script>
They have $gid & $fid. $fid is also used in the iframe id ( "spFrame" . $fid )