Another view on Youtube (Google) vs. Microsoft
I was thinking about possible explanations and solutions for the current YouTube on WP problem.
I think that Google wants to retain control over YouTube. Obviously, it's very hard to do that if you don't make the app yourself. Now, Microsoft built their own app and called it "YouTube". This way Google can not make any changes without asking Microsoft.
Microsoft has built their own Xbox Music app entirely in HTML5. And they promote HTML5 as one of two ways to make Windows8/RT apps. I am surprised if they don't have this capability in Windows Phone 8.