This trick will allow you to create a Divi friendly footer (within the front-end builder) and then via a child theme modification to the footer.php file, have it echo throughout your site.
<style>.embed-container { position: relative; padding-bottom: 56.25%; height: 0; overflow: hidden; max-width: 100%; } .embed-container iframe, .embed-container object, .embed-container embed { position: absolute; top: 0; left: 0; width: 100%; height: 100%; }</style>
<div class="embed-container"><iframe src="https://www.youtube.com/embed/vnN44Z9UTQM" frameborder="0" allowfullscreen="allowfullscreen"></iframe></div>
And the code to enter in your footer.php file. Make sure to replace the relevant post # (the 999 below) with your own. Replace curly brackets below with square ones below as well { = [.
<?php echo do_shortcode('{et_pb_section global_module="999"}{/et_pb_section}'); ?>;