.about-section {
    padding: 30px 0 70px;
    position: relative;
}

.videomax {
    display:block;
}
.videomin{
    display: none;
}

@media only screen and (max-width: 600px) {
    .videomax {
        display:none;
    }
    .videomin{
        display:block;
    }
    
}