Video Not Responsive Except On “Page”

I resolved this a while back by adding this to my functions file. Hopefully, it will help someone in the future. Seems to cover everything we needed.

// Add Responsive To Embeds With CSS Class "video-container"
function div_wrapper_video_container($content) {
    // match any iframes
    $pattern = '~<iframe.*</iframe>|<embed.*</embed>~';
    preg_match_all($pattern, $content, $matches);

    foreach ($matches[0] as $match) {
        // wrap matched iframe with div
        $wrappedframe = '<div class="video-container">' . $match . '</div>';

        //replace original iframe with new in content
        $content = str_replace($match, $wrappedframe, $content);
    }

    return $content;    
}
add_filter('the_content', 'div_wrapper_video_container');