#recXXXX .t396__artboard {
    position: relative;
    overflow: hidden;
}

#recXXXX .t396__artboard::before {
    content: "";
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: black;
    z-index: -2;
}

/* Само видео */
#recXXXX .t396__artboard::after {
    content: "";
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    z-index: -1;
    background: url("ТУТ_ССЫЛКА_НА_ВИДЕО.mp4") center center / cover no-repeat;
}