@Pesala
Honestly, I couldn't say whether I had watched something in full-screen mode; but it's definitely something I couldn't rule out.
And I have to add, that I'm kind of a tab addict, e.g. currently 103 tabs open (some stacked). Boy, that sounds so wrong :). But it's awesome that it handles these quantities so well.
But yes, it could have been a full-screen video.
Speaking of full-screen: another observation I made: sometimes after full-screen the browser window expands ALL the way to the bottom, covering the Win7 taskbar. No biggie, just an observation I made 2 or 3 times.