JSFiddle - React, Tailwind, and code Playground

HTML

<div class="thumbnail-wrapper">
    <img src="http://img.youtube.com/vi/XXCAtZoCECQ/0.jpg" />
    <button></button>
</div>

CSS

.thumbnail-wrapper {
    display:inline-block;
    position:relative;
}
.thumbnail-wrapper button {
    position:absolute;
    top:50%;
    left:50%;
    width:100px;
    height:100px;
    border:2px solid #fff;
    border-radius:100px;
    background:rgba(255, 255, 255, 0.2);
    -webkit-transform:translate3d(-50%, -50%, 0);
    -moz-transform:translate3d(-50%, -50%, 0);
    transform:translate3d(-50%, -50%, 0);
}
.thumbnail-wrapper button:before {
    content:"";
    width: 0;
    height: 0;
    border-style: solid;
    border-width: 25px 0 25px 25px;
    border-color: transparent transparent transparent #ffffff;
    position:absolute;
    top:25px;
    left:42px;
}
.thumbnail-wrapper button:hover, .thumbnail-wrapper button:after:hover {
    box-shadow:0 0 0 4px rgba(150, 150, 100, 0.7);
}