Thus, even if you have access to a movie for free through Netflix, using the Voice Search for that movie will only bring up Amazon's paid options.
This is also the problem with the Xbox One, it only searches the MS store and none of your apps like Netflix or Hulu. It also can't search your DVR to suggest shows/movies you have already recorded.
Like AMD's Mantle API, it promises reduced CPU overhead and lower-level access to graphics hardware. But DirectX 12 won't be limited to one vendor's hardware.
Mantle will work on this hardware as well, and won't be limited to one vendor's operating system. From AMD's Mantle FAQ