You can use a video wrapper insead a image wrapper in case you need to play a video in background
<div class="sq-slick hero-big" data-fade="true" data-speed="500" data-ease="linear">
<!--Slide 01-->
<div>
<div class="caption-content">
...
</div>
<div class="video-wrapper ">
<iframe src="https://www.youtube.com/embed/W0LHTWG-UmQ?controls=0&showinfo=0&rel=0&autoplay=1&loop=1&playlist=W0LHTWG-UmQ" frameborder="0" allowfullscreen></iframe>
</div>
</div>
<!--Slide 02-->
<div> ... </div>
...
</div>