Vuforia video background obstructs Unity 5 UI

As the title says, i don’t see the same thing I see in editor.
My scene consists of Vuforia camera and a target + ZXing’s QRcode reader script on one of the UI elements. UI main button always visible, all the rest is hidden on start.

By fiddling around I realized, that UI is not abstructed, but resized wierdly, when it is on Vuforia Camera.
When I detached it from camera, it appeared horizontally flipped.

The right way to do a UI with Vuforia plugin is not to delete main camera, but create Vuforias ARcamera along with it. And to do all UI on that original Main Camera. This saved me after a week of madness.

And one more thing: never touch that AR Camera settings! Just don’t.