JSFiddle - React, Tailwind, and code Playground

HTML

<div class=dcsns-youtube>
    <span class="section-thumb">
        <a href="some-link"><img src="http://img.youtube.com/vi/m4-1FZeoBtQ/default.jpg"></a>
    </span>
    <span class="section-title">
        <a href="some-link">Text 1</a>
    </span>
  </div>
<div>
  <div class=dcsns-youtube>
    <span class="section-thumb">
        <a href="some-link"><img src="http://img.youtube.com/vi/m4-1FZeoBtQ/default.jpg" alt=""></a>
    </span>
    <span class="section-title">
        <a href="some-link">Text2</a>
    </span>
<div>

JavaScript

$('.dcsns-youtube').each(function(){
  $('.section-thumb a', this).attr('title', $('.section-title', this).text());
});