JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.1.0/js/bootstrap.min.js"></script>
<link rel="stylesheet" type="text/css" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.1.0/css/bootstrap.min.css">
<div class="company__box pop" data-toggle="modal" data-target="#ModalVideo">
 <span>
  Assista ao nosso
   vídeo institucional
   </span>
</div>

<!-- Modal Vídeo-->
 <div class="modal fade" id="ModalVideo" tabindex="-1" role="dialog" aria-labelledby="ModalVideoLabel" aria-hidden="true">
   <div class="modal-dialog modal-lg" role="document">
     <div class="modal-content content_modal">
       <button type="button" class="close" data-dismiss="modal" aria-label="Close">
         <span aria-hidden="true">&times;</span>
       </button>
       <div class="corpo_video">
         <iframe width="100%" height="450px" src="https://www.youtube.com/embed/1RRI3Wykugo?enablejsapi=1">
         </iframe>
       </div>
     </div>
   </div>
 </div>

JavaScript

function paraVideo(){
   document.querySelector('.corpo_video iframe')
   .contentWindow.postMessage('{"event":"command","func":"pauseVideo","args":""}', '*');
}

$('#ModalVideo').on('hide.bs.modal', paraVideo);