.bannerVideo {
    float: left;
    width: 100%;
}

.bannerVideo video {
    float: left;
    width: 100%;
}

.bannerVideo .videoMobile {
    display: none;
}

@media only screen and (max-width: 768px) {

    .bannerVideo .videoDesktop {
        display: none;
    }

    .bannerVideo .videoMobile {
        display: block;
    }

}