Because there are so many different makes, models, and software versions of smart TVs out there, it makes testing them impossible, and so we do not officially support them.
The compatible streaming devices that our app can cast to are: the Apple TV, Chromecast, Fire TV, or Roku. Even though some of these devices have TV in the name they are NOT televisions. They all belong to a group of devices called "streaming devices" that connect to your existing television. A streaming device is any device that uses the internet to play videos or other content and the videos themselves are not saved to the device.
It's possible you have a television that has one of these devices built into it already. That would make it possible to cast from our app directly to your television. If you don't have it built into your television, you have to buy one and plug it into the TV like you would with a cable box or Blu-ray player.
Not all apps connect to streaming devices in the same way, therefore even if the YouTube app is able to cast to your TV, that doesn't mean the Gemiini app will. They use different plugins and those plugins can only talk to the devices they're built for.
I hope that helps clear up the confusion.