Some videos have black lines on top and bottom of the video. It's nice to have zoom option for them not to loose display space. I use for myself a small script (not perfect):
```
var zoomFactor = 1;
document.onwheel = function(event) {
if(event.altKey) {
zoomFactor = zoomFactor + event.wheelDelta / 1200;
var newHeight = window.innerHeight * zoomFactor;
var newTop = -1 * parseInt((newHeight - window.innerHeight) / 2);
document.getElementsByClassName('sizing-wrapper')[0].style.height = parseInt(newHeight) + "px";
document.getElementsByClassName('sizing-wrapper')[0].style.top = parseInt(newTop) + "px";
}
}
```