What's especially awesome is when they take a minute to load, after you've switched to a different tab and have no idea which site is playing them. You get to hunt through all your tabs just to discover who's playing such an awesome ad!

auto-play video ads should be disabled at the OS level

Grab adblock and flashblock. And noscript if you're feeling hardcore. The web gets way better.

Add https://userscripts.org/scripts/review/149647 as well to disable autoplay of html5-videos.

Nothing stops HTML5 video from autoplaying, sadly.

Look above you friend.