/*** to quick css - better to place with the concerning page ID ***/

.mfp-iframe-holder {
  padding: 0px !important; 
}

.mfp-iframe-holder .mfp-content {
  height: 90vh !important;  /*** the wanted height ***/
  width: 160vh;  /*** the calculated width is then ***/
}

.mfp-iframe-scaler {
  padding-top: 56.25%; /*** depends on video aspect-ratio ***/
  position: relative;
  top: 50%;
  transform: translateY(-50%) !important;
}