I saw the weird subtle pattern and first freaked out that my monitor's backlight was failing (high flicker rate revealing LCD refresh patterns). I also was playing a video with the browser in the background and it was choppy, and I first thought it was my video player messing up until I realized the web page had some pointless background animation.

I just tested again and even my cursor gets jump over the page. Amazing they'd do this for such a subtle, useless effect.