@keyframes rounded-mask-reveal {
  from {
    clip-path: inset(10% 10% 10% 10% round 30px);
  }
  to {
    clip-path: inset(0% 0% 0% 0% round 30px);
  }
}

video {
  animation: rounded-mask-reveal linear both;
  animation-timeline: view();
  animation-range: cover 0% cover 50%;
}

It's always been annoying to have highlighting with inline code tags too... but not anymore! See, I can say function rad() {} or a { color: red; }

Holy cow!