.my-video-dimensions {
    width: 640px !important;
    height: 360px !important;
}

@media only screen and (max-width: 1400px) {
    .my-video-dimensions {
        width: 530px !important;
        height: 300px !important;
    }
}
@media only screen and (max-width: 1200px) {
    .my-video-dimensions {
        width: 465px !important;
        height: 260px !important;
    }
}
@media only screen and (max-width: 600px) {
    .my-video-dimensions {
        width: 330px !important;
        height: 187px !important;
    }
}