playButton.css

.playbutton {
    position: absolute;
    z-index: 10;
    top: 50%;
    left: 50%;
    transform: translateX(-50%) translateY(-50%);
    box-sizing: content-box;
    display: block;
}
.playbutton::before {
    content: "";
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translateX(-50%) translateY(-50%);
    box-sizing: content-box;
    display: block;
    width: 80px;
    height: 80px;
    background: #4b4b4bc7;
    border-radius: 50%;
}
.playbutton span {
    display: block;
    margin-left: 8px;
    position: relative;
    z-index: 3;
    width: 0;
    height: 0;
    border-left: 24px solid #fffff7;
    border-top: 14px solid transparent;
    border-bottom: 14px solid transparent;
}
div.shaka-video-container:hover .playbutton::before {
    background: #9b9b9bc7;
}