.c-video-duo { background: #000; }
.c-video-duo .wrap { position: absolute; inset: 0; overflow: hidden; }
.c-video-duo video {
  position: absolute; inset: 0; width: 100%; height: 100%;
  object-fit: cover;
  transition: opacity 120ms ease-out, filter 120ms ease-out;
  pointer-events: none;
}
.c-video-duo .top    { z-index: 2; }
.c-video-duo .bottom { z-index: 1; }