Tbd how Alexa responds when you vocalize complaints about unavailable content
"Amazon, not surprisingly, is pitching the Fire TV Cube as the perfect Frankengadget for your TV, something that not only gives you full Echo features but is supposed to drastically simplify your TV experience. But as with any hardware product from a company that has some services skin in the game, the Fire TV Cube is not a perfectly agnostic streaming platform.Amazon's New Fire TV Device Is a Voice-Controlled Cube -- Wired
Like every other FireOS device, the Fire TV Cube doesn't play content purchased through iTunes. Apple TV, on the other hand, now streams Amazon Prime Video, so Apple has the distinct advantage there. More important is FireOS's lack of a native YouTube app. Thanks to a spat that Google and Amazon can't seem to resolve, your only option for watching YouTube videos on an Amazon device right now is to use a browser."