How to fix a stuttering HTML5 video on desktop view?

At this moment I've implemented a background HTML5 video in my site, and for some kind of reason it stutters like crazy on desktop browsers like Chrome and FireFox.

However, when I check the HTML5 video on my iPhone 6 Plus (Safari and Chrome) it works perfectly fine and runs incredibly smooth.

Site: http://www.happiness-design.com

Can anyone please help me in fixing the stutter on desktop?

Thanks in advance, Chris