.youtube {
    background-position: center;
    background-repeat: no-repeat;
    position: relative;
    display: inline-block;
    overflow: hidden;
    transition: all 200ms ease-out;
    cursor: pointer;
}
.youtube .play {
    background: url('../img/youtube-play-btn.png') no-repeat; /*ВАЖНО: здесь укажите адрес до изображения*/
    background-position: 0 -50px;
    -webkit-background-size: 100% auto;
    background-size: 100% auto;
    position: absolute;
    height: 50px;
    width: 69px;
    transition: none;
    top:0;
    left:0;
    right:0;
    bottom:0;
    margin:auto;
}
.youtube:hover .play {
    background-position: 0 0;
}