JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
  <iframe src="https://player.vimeo.com/video/135335257?autoplay=false" width="640" height="360" frameborder="0" webkitallowfullscreen="" mozallowfullscreen="" allowfullscreen=""></iframe>
</div>

CSS

body, html {height:100%; margin:0;}
.container {
    position: absolute;
    top: 0;
    overflow: hidden;
}

JavaScript

var min_w = 300; // minimum video width allowed
var vid_w_orig;  // original video dimensions
var vid_h_orig;

jQuery(function() { // runs after DOM has loaded

    vid_w_orig = parseInt(jQuery('iframe').attr('width'));
    vid_h_orig = parseInt(jQuery('iframe').attr('height'));

    jQuery(window).resize(function () { resizeToCover(); });
    jQuery(window).trigger('resize');
});

function resizeToCover() {

    // set the video viewport to the window size
    jQuery('.container').width(jQuery(window).width());
    jQuery('.container').height(jQuery(window).height());

    // use largest scale factor of horizontal/vertical
    var scale_h = jQuery(window).width() / vid_w_orig;
    var scale_v = jQuery(window).height() / vid_h_orig;
    var scale = scale_h > scale_v ? scale_h : scale_v;

    // don't allow scaled width < minimum video width
    if (scale * vid_w_orig < min_w) {scale = min_w / vid_w_orig;};

    // now scale the video
    jQuery('iframe').width(scale * vid_w_orig);
    jQuery('iframe').height(scale * vid_h_orig);
    // and center it by scrolling the video viewport
    jQuery('.container').scrollLeft((jQuery('iframe').width() - jQuery(window).width()) / 2);
    jQuery('.container').scrollTop((jQuery('iframe').height() - jQuery(window).height()) / 2);

    
};