Hi,
try this code:
<!--Card-->
<div class="card">
<!--Card image-->
<video class="img-fluid" playsinline autoplay muted loop>
<source src="https://mdbootstrap.com/img/video/animation-intro.mp4" type="video/mp4">
</video>
<!--Card content-->
<div class="card-body">
<!--Title-->
<h4 class="card-title">Card title</h4>
<!--Text-->
<p class="card-text">Some quick example text to build on the card title and make up the bulk of the card's content.</p>
<a href="#" class="btn btn-primary">Button</a>
</div>
</div>
<!--/.Card-->
Best,
Marta