.videoBlock{
    width: 45%;
    text-align: center;
    margin-left: 30px;
}
.videoBlock video{
    max-width: 100%;
    height: auto;
    vertical-align: bottom;
}
@media (max-width: 767px) {
    .mainVisual .videoBlock{
        width: 100%;
        margin-top: 30px;
        display: flex;
        justify-content: center;
        margin-left: 0;
    }
}