I inserted a YouTube iframe code inside a div element.
<div id="box">
<iframe width="300" height="315"
src="//www.youtube.com/embed/82fn4mcNGJY"
frameborder="0" allowfullscreen></iframe>
</div>
After applying CSS to scale this div tag, I noticed that Firefox is unable to display the video properly.
#box{
transform: scale(1.06667);
transform-origin: 0px 0px 0px;
}