This is your magical TV. Nobody knows, but its screen works like a portal. At any moment, you can just walk through the screen and end up wherever you want, from hockey games to anime, from sci-fi movies to weather forecasts, and so on.
It works flawlessly and perfectly, always operational. When you teleport, everyone will hear you and see you (since you’ll actually be there until you decide to go back). Though, no one will know who are you, where you came from or what are you doing there.
All you have to do is to pick a program and walk through the screen - boom, you’re there.
By the way, if it’s live, the whole world will see you on their screens too (for example, if it’s a news conference or a sports event). If it’s fictional or not live, no one will see you (for example, if it’s a cartoon, an anime or a movie).