#video_cont {
  width: 90%;
  max-width: 1000px;
  margin: 20px auto 30px auto;
  text-align: center;
}
#video_cont video {
  display: block;
  width: 100%;
  height: auto;
  max-height: 70vh;
  margin: 0 auto;
  border: 2px solid #000;
  background: #000;
  object-fit: contain;
}
@media screen and (max-width:479px) {
  #video_cont {
    width: 90%;
    margin: 20px auto 20px auto;
  }
  #video_cont video {
    max-height: 60vh;
  }
}