<title>Netflix Chrome Book Log-in</title>
<embed src="https://signup.netflix.com/Login?country=1&rdirfdc=true" width="900" height="780" />
Netflix puts a link in there log-in page to this Page above "Netflix Chrome Book Log-in". The whole netflix site becomes embedded in the above html5 page. I imagine background API that that streams to IOS and Android would now streams to Chrome Book. Silverlight sucks. Your logic alludes me, if the Netflix site is running on HTML5 how would encrypted DRM work?
My point is if your put this above page on your own domain you could login in to netflix and watch movies on your Chrome Book too. This is the power of the embed tag in html5.
Authentication is not the same thing as encryption.
Netflix need both.
They need you to log in, so that they know who you are and hence are entitled to rent movies. They also need encryption to ensure that when you rent a movie, they can be sure you won't save a local copy which would be easy for you to share with your thousands of friends!
Authentication doesn't need any clever browser tech and works on just about anything. The encryption for movie playback, together with advanced stuff like automatically switching the stream quality based on your connection speed is hard and not in the HTML5 standard.