@Neme: No, I think you'll find that's valid code! :) That code at 17:30 shows the longhand way of switching between different Visual States based on the window width, something we can now do more easily in XAML using adaptive triggers.
@LukasNeoproud: The difference from Android is that we are going to be pushing updates to end users to keep their machines up to date. Android device suppliers have not done a good job of updating existing devices in the field.
The other way we can support is that the Windows Store can manage multiple versions of an app, so any users who have not updated their machines will still get the old version of the app.