Making another attempt to provide the code. Replacing the embed-responsive and embed-responsive-16by9 classes with ratio and ratio-16x9 fixed the responsiveness. However the video’s then took up the entire viewport. I adjusted this by setting max-width/max-height on the iframe. Unfortunately, now the carousel-items are stuck to the left side instead of centered on the page. And the carousel-indicators are in the middle of the footer (not included here)
<!DOCTYPE html>
<html data-bs-theme="light" lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, shrink-to-fit=no">
<title>HomePage</title>
<link rel="stylesheet" href="assets/bootstrap/css/bootstrap.min.css">
<link rel="stylesheet" href="assets/css/redra-forms.css">
<link rel="stylesheet" href="assets/css/redra-styles.css">
<link rel="stylesheet" href="assets/css/Footer-Dark-icons.css">
<link rel="stylesheet" href="https://fonts.googleapis.com/css2?family=Material+Symbols+Outlined:opsz,wght,FILL,GRAD@20..48,100..700,0..1,-50..200">
<link rel="stylesheet" href="https://fonts.googleapis.com/css2?family=Poppins:wght@400;500;600;700&display=swap">
<link rel="stylesheet" href="assets/css/redra-carousel.css">
<link rel="stylesheet" href="assets/css/styles.css">
</head>
<body>
<nav id="mainNav" class="navbar navbar-expand-lg fixed-top">
<div id="nav-container" class="container"><a class="navbar-brand logo text-white" href="#"><img class="rounded-circle img-fluid" id="logo-image" src="assets/img/redDragonLogo-small.jpg"></a><button class="btn navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navcol-1"></button>
<div id="navcol-1" class="collapse navbar-collapse">
<ul class="ms-auto navbar-nav">
<li class="nav-item"><a class="nav-link text-white" href="/registration/"><img src="assets/img/register-button.png"></a></li>
<li><a class="nav-link text-white" href="/login/"><img src="assets/img/login-button.png"></a></li>
</ul>
</div>
</div>
</nav>
<div class="d-flex flex-column flex-grow-1 mb-2">
<div class="text-center carousel slide carousel-fade" id="redra-fade" data-bs-ride="carousel">
<div class="carousel-indicators"><button class="btn active" type="button" data-bs-target="#redra-fade" data-bs-slide-to="0" aria-current="true" aria-label="Video 1"></button><button class="btn" type="button" data-bs-target="#redra-fade" data-bs-slide-to="1" aria-current="true" aria-label="Video 2"></button><button class="btn" type="button" data-bs-target="#redra-fade" data-bs-slide-to="2" aria-current="true" aria-label="Video 3"></button><button class="btn" type="button" data-bs-target="#redra-fade" data-bs-slide-to="3" aria-current="true" aria-label="Video 4"></button><button class="btn" type="button" data-bs-target="#redra-fade" data-bs-slide-to="4" aria-current="true" aria-label="Video 5"></button><button class="btn" type="button" data-bs-target="#redra-fade" data-bs-slide-to="5" aria-current="true" aria-label="Video 6"></button></div>
<div id="redra-inner" class="carousel-inner">
<div class="carousel-item active">
<div class="embed-responsive-embed-responsive-16by9"><iframe allowfullscreen="" frameborder="0" src="https://www.youtube.com/embed/xrNJZmA9aL8" class="embed-responsive-item" title="5-Plane Formation through British Columbia, Canada 🇨🇦" allow="accelerometer; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin"></iframe></div>
</div>
<div class="carousel-item">
<div class="embed-responsive embed-responsive-16by9"><iframe allowfullscreen="" frameborder="0" src="https://www.youtube.com/embed/liA3fvFjGUE" class="embed-responsive-item" title="YouTube video player" allow="accelerometer; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin"></iframe></div>
</div>
<div class="carousel-item">
<div class="embed-responsive embed-responsive-16by9"><iframe allowfullscreen="" frameborder="0" src="https://www.youtube.com/embed/M8-cLvniyuM" class="embed-responsive-item" title="YouTube video player" allow="accelerometer; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin"></iframe></div>
</div>
<div class="carousel-item">
<div class="embed-responsive embed-responsive-16by9"><iframe allowfullscreen="" frameborder="0" src="https://www.youtube.com/embed/G1OOdPoDM3M" class="embed-responsive-item" title="YouTube video player" allow="accelerometer; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin"></iframe></div>
</div>
<div class="carousel-item">
<div class="embed-responsive embed-responsive-16by9"><iframe allowfullscreen="" frameborder="0" src="https://www.youtube.com/embed/GghxxO05k7k" class="embed-responsive-item" title="YouTube video player" allow="accelerometer; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin"></iframe></div>
</div>
<div class="carousel-item">
<div class="embed-responsive embed-responsive-16by9"><iframe allowfullscreen="" frameborder="0" src="https://www.youtube.com/embed/ZeZICcr4fiI" class="embed-responsive-item" title="YouTube video player" allow="accelerometer; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin"></iframe></div>
</div>
</div>
</div>
<div class="mt-auto" id="footer">
<footer class="text-center bg-dark">
<div class="text-white py-4 py-lg-5">
<ul class="list-inline">
<li class="list-inline-item me-4"><a href="#">Battle Briefing</a></li>
<li class="list-inline-item me-4"><a href="#">Battle Schedule</a></li>
<li class="list-inline-item"><a href="#">Battle Videos</a></li>
</ul>
<ul class="list-inline">
<li class="list-inline-item me-4"> <svg class="bi bi-facebook text-light" xmlns="http://www.w3.org/2000/svg"
width="1em" height="1em" fill="currentColor" viewBox="0 0 16 16">
<path d="M16 8.049c0-4.446-3.582-8.05-8-8.05C3.58 0-.002 3.603-.002 8.05c0 4.017
2.926 7.347 6.75 7.951v-5.625h-2.03V8.05H6.75V6.275c0-2.017 1.195-3.131 3.022-3.131.876
0 1.791.157 1.791.157v1.98h-1.009c-.993 0-1.303.621-1.303
1.258v1.51h2.218l-.354 2.326H9.25V16c3.824-.604 6.75-3.934 6.75-7.951">
</path>
</svg></li>
<li class="list-inline-item me-4"><svg class="bi bi-twitter text-light" xmlns="http://www.w3.org/2000/svg"
width="1em" height="1em" fill="currentColor" viewBox="0 0 16 16">
<path d="M5.026 15c6.038 0 9.341-5.003 9.341-9.334 0-.14 0-.282-.006-.422A6.685 6.685
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</path>
</svg>
</li>
<li class="list-inline-item"><svg class="bi bi-instagram text-light" xmlns="http://www.w3.org/2000/svg"
width="1em" height="1em" fill="currentColor" viewBox="0 0 16 16">
<path d="M8 0C5.829 0 5.556.01 4.703.048 3.85.088 3.269.222 2.76.42a3.917 3.917
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</path>
</svg></li>
</ul>
<p class="mb-0"><span style="color: rgb(216, 216, 216); background-color: rgb(25, 29, 31);">Copyright © 2025 =REDRA</span><span style="color: rgb(141, 203, 226); background-color: rgb(25, 29, 31);">=</span></p>
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</footer>
</div>
</div>
<script src="assets/bootstrap/js/bootstrap.min.js"></script>
<script src="assets/js/carousel.js"></script>
</body>
</html>
'''