JSFiddle - React, Tailwind, and code Playground

HTML

<video controls>
    <source src="http://dynamic-slideshow.de/cgi-bin/IMG_0010.MP4" />
</video>
<span id="dimensions"></span>

CSS

#dimensions {
    display: block;
    font-weight: bold;
    color: #4c4c4c; 
}

JavaScript

$(function() {
    var video = document.getElementsByTagName("video")[0];
    var dimensions = document.getElementById("dimensions");
    dimensions.innerHTML = video.videoHeight + "x" + video.videoWidth;
   
});