styles.css

*,
*::before,
*::after {
	box-sizing: border-box;
}

body {
	margin: 0;
	height: 100vh;
	background-color: #333;
	display: flex;
	justify-content: center;
	align-items: center;
}
section {
	display: flex;
	justify-content: center;
	align-items: center;
}
.video-container {
	--borderLeft: 0;
	--borderRight: 0;
	--borderTop: 0;
	--borderBottom: 0;
	position: relative;
	width: 30.2em;
	height: 17em;
	cursor: pointer;
}

.video-container::before,
.video-container::after {
	content: "";
	border: 0 solid red;
	pointer-events: none;
	position: absolute;
	width: 0;
	height: 0;
}
.video-container::before {
	top: 0;
	left: 0;
	border-top-width: 0.25rem;
	border-left-width: 0.25rem;
	width: var(--borderTop);
	height: var(--borderLeft);
}
.video-container::after {
	bottom: 0;
	right: 0;
	border-bottom-width: 0.25rem;
	border-right-width: 0.25rem;
	width: var(--borderBottom);
	height: var(--borderRight);
}

video {
	width: 100%;
	height: 100%;
}