Enqueue fitvids from https://github.com/davatron5000/FitVids.js | Props to @realFATmedia & @krogsgard

enqueue fitvids

// Add to functions file
add_action('wp_enqueue_scripts', 'child_javascript_files');
 
function child_javascript_files() {
        wp_register_script( 'fitvids', get_stylesheet_directory_uri() . '/js/jquery.fitvids.js', array('jquery'), '1.0', true );
        wp_register_script( 'loadfitvids', get_stylesheet_directory_uri() . '/js/load.fitvids.js', array('fitvids'), '1.0', true );
        wp_enqueue_script( 'fitvids' );
        wp_enqueue_script( 'loadfitvids' );
 }
 
 
// Create a file named load.fitvids.js and enter the following
  jQuery(document).ready(function($){
    // Target your .container, .wrapper, .post, etc.
    $(".videowrap").fitVids();
  });