<Tell me who else has implemented HTML5 on an open OS at the same level shown in the video.>
HTML5 is not a platform. It's a language.
Maybe you need to listen to the developer of the Facebook app and hear why he went from HTML5 to an Objective-C app.
"Building on native iOS gives us a major opportunity to keep making the app faster, more reliable and feature-rich. Whether you have 30 seconds or an entire train ride to use Facebook we want you to have a fast and satisfying experience. We truly believe mobile is the best platform for Facebook, and the new Facebook for iOS is just one of our steps to ensure you have best Facebook experience anytime, anywhere. "