<body>
    <div class="video">
        <video  autoplay muted src="https://youtu.be/pGbIOC83-So"></video>
    </div>
    <div class="backlight">
        <video autoplay muted src="https://youtu.be/pGbIOC83-So"></video>
    </div>
</body>
*{
    padding: 0;
    margin: 0;
    box-sizing: border-box;
}
body{background: #000;
    height: 100vh;
    display: flex;
    align-items: center;
    justify-content: center;
}
.video{
    position: absolute;
    
    width: 50%;
    z-index: 1;
}
.backlight{
    width: calc(50% + 50px);
    filter: blur(38px);
}
.backlight::before{
    content: "";
    position: absolute;
    display: inline-block;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: linear-gradient(0deg, transparent calc(100% - 14px), black 100%),
                linear-gradient(180deg, transparent calc(100% - 14px), black 100%),
                linear-gradient(90deg, transparent calc(100% - 25px), black 100%),
                linear-gradient(270deg, transparent calc(100% - 25px), black 100%);
}       
video{
    display: block;
    width: 100%;
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.