I am going to say what I have said in 9to5mac:
0:09 - I think this is a good idea but the ability to choose which button I want should be in the Setting App.
0:16 - No! This is a lock screen, it is supposed to lock. If someone steals your phone, just turn on Airplane mode and suddenly Find My iPhone becomes useless.
0:38 - Same as above - this is a lock screen, it is supposed to lock the phone.
0:43 - Nice, really nice. Revamped warnings interface, something that I loved and the idea of replying like that is pretty neat.
0:50 - The home screen is a app launcher. I think widgets should go to the Notification Center. In Settings app you could choose which Widgets you would like to add into Notification Center (something you can already do for the Twitter/Facebook, Weather and Stock widgets, but with a lot more widgets. I think Apple should let 3rd party apps to take advantage of the notification center or, alternatively, launch a new App Store section with Widgets. But they should not go to the Home Screen.
1:48 - Good Idea, implementation is not that intuitive. These kind of settings should be present on a Widget in Notification Center.
2:14 - Nice, nice, nice. Interface not that nice. I think apple should remove those horrible Shelf effects in iBooks, iTunes and Newstand. The Safari interface is really good, nice job!
3:06 - I don't like Mission Control. Live previews are useless - the apps' icons make the OS more consistent because the same symbol is used in the launcher and in the apps' switcher; the live previews take a lot more RAM to run not to mention true multitasking that would require a lot more of power draining the battery faster. The idea of closing all the apps is nice and should be implemented but I think Apple should make a more conservative approach adding multiple rows to the current app switcher so we could see more than 4 opened apps at once (90% of the screen is useless anyway, so the app switcher should allocate the screen in a better way). The way you designed the interface makes impossible to see more than one app at once in the iPhone, which is exactly the opposite that should be done.