I have a video tag with the autoplay attribute on. It's "hidden" in that it's nested in a container with display: none applied.
However, CPU usage for this page's tab in Chrome seems idling high (around 20%). There is nothing else on the page.
Do video tags pause autoplaying when hidden? For reference, WebKit-based Safari in iOS 10 pauses autoplaying on the video tag when not visible on screen (https://webkit.org/blog/6784/new-video-policies-for-ios/). But I'm unconfirmed if Chrome does, since it uses the Blink fork of Webkit.
Chrome Mac 55.0.2883.75 (64-bit)