全幅の背景ビデオでは、html5のdata-bg-video = "video path"クラスを使用できます。下記の デモの例は、データの背景ビデオパスを挿入するだけです。
<section class="mbr-section mbr-section-hero mbr-section-full " id="header4-0"
data-bg-video="https://www.youtube.com/watch?v=La5GyrphjK0">
<div class="mbr-overlay" style="opacity: 0.5; background-color: rgb(0, 0, 0);"></div>
<div class="mbr-table-cell">
<div class="container">
<div class="row">
<div class="mbr-section col-md-10 col-md-offset-2 text-xs-right">
<h1 class="mbr-section-title display-1">VIDEO BACKGROUND</h1>
<p class="mbr-section-lead lead">Intro with background video and color overlay. Text and buttons are aligned to right. Mobirise helps you cut down development time by providing you with a flexible website editor with a drag and drop interface.</p>
<div class="mbr-section-btn"><a class="btn btn-lg btn-success" href="#">Demo Button</a> <a class="btn btn-lg btn-warning" href="#">Demo Button</a></div>
</div>
</div>
</div>
</div>
<div class="mbr-arrow mbr-arrow-floating" aria-hidden="true"><a href="#next"><i class="mbr-arrow-icon"></i></a></div>
</section>
'data-bg-video ="ビデオパス "とはどういう意味ですか?それはクラスではありません – georgej