A może po prostu użyj grid-a click ^^ ^^
<section class="video-grid-container">
<div class="frame_1">
<iframe width="560" height="315" src="https://www.youtube.com/embed/QNTeq4QdOsQ" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
</div>
<div class="frame_2">
<iframe width="560" height="315" src="https://www.youtube.com/embed/qugY8axtvWY" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
</div>
<div class="frame_3">
<iframe width="560" height="315" src="https://www.youtube.com/embed/LadpP5XR1aM" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
</div>
<div class="frame_4">
<iframe width="560" height="315" src="https://www.youtube.com/embed/r1ZtMCr0Pr4" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
</div>
</section>
*, *:before, *:after {
-webkit-box-sizing: inherit;
-moz-box-sizing: inherit;
box-sizing: inherit;
}
html, body {
padding: 0;
margin: 0;
border: 0;
}
.video-grid-container {
display: grid;
grid-template-columns: 1fr 1fr;
grid-template-rows: 1fr 1fr;
gap: 1em;
grid-template-areas: "frame_1 frame_2" "frame_3 frame_4";
max-width: 20vw;
margin-top: 50px;
margin-left: auto;
margin-right: auto;
justify-content: center;
align-content: center;
}
.frame_1 { grid-area: frame_1; }
.frame_2 { grid-area: frame_2; }
.frame_3 { grid-area: frame_3; }
.frame_4 { grid-area: frame_4; }