.iotcenter{text-align: center;}

.movie-wrap {
     position: relative;
     padding-bottom: 56.25%; /*アスペクト比 16:9の場合の縦幅*/
     height: 0;
     overflow: hidden;
}
 
.movie-wrap iframe {
     position: absolute;
     top: 0;
     left: 0;
     width: 100%;
     height: 100%;
}