.fluid-width-video-wrapper:before {
    content:"";
    background-image: url(https://www.mywebsitelooksawesome.com/wp-content/uploads/2018/02/header-cutout.png);
    position: absolute;
    top: 0;
    left: 0;
    z-index: 1;
    width: 100%;
    height: 100%;
    background-size: cover;
}