Canvas: Block Autoplay for embedded websites

Currently, embedding a linked website in canvas with autoplaying video simply allows the video to play automatically when the canvas is loaded, and at full volume. This behaviour is annoying for my use cases, and I would expect for most others. Similarly I expect that its utility sharply declines with more than a single video autoplaying simultaneously.

I suggest that like FireFox, automatic video or audio playback should be prevented until focused upon or at least that audio should be muted until focused upon.