The experience you can provide with an HTML5 app are many times subpar as compared to a native app. Note how facebook abandoned their HTML5 app and went native.
YouTube's API only requires the video player itself to be in HTML5, the rest of the app can be native or whatever the hell you want. The engineering work here is youtube hands you an HTML snippet (specifically an <iframe>), and you plop that into a UIWebView where you want the inline video to be and you're done.
The issue then is that Google will complain that the rest of the app doesn't adhere to all of Google's terms of services regarding displaying of ads, which are difficult to implement without their blessing.
Calm down. So you think a youtube app with a big rectangle that plays video and another one that allows you to type the url is the right experience? Video playback is just one aspect of it. search, lists, subscriptions, commenting, uploading, tagging, etc.
As for facebook's app, I was commenting about HTML5 still not being the best option for mobile app development.
LinkedIn also abandoned their HTML 5 mobile app experiences.
the biggest problem with HTML 5 video is that it does not support adaptive bitrate streaming. notice that the desktop experience of YouTube still uses a flash player instead of an HTML 5 video player. notice that apple used QuickTime as their default player on their site.
in short, HTML 5 video player is an absolute last resort player.
Don't get me started on how terrible all of it is on Linux. Incapable of dual screen full screen in flash, HTML5 has to buffer every time you enter full screen mode.
Incredible slow performance, buggy, crashes.
I actually have to boot into Windows VM just to watch flash/youtube.
Sencha's app was a proof-of-concept. Their motivation was to show how and where facebook was "full-of-shit" which they did beautifully. If you read their respective articles, you can discern for yourself.
