A photo like this needs careful balancing: the TV, the room, and the outside.

1. First, as always, set the ambient exposure. Set your camera to match the outside.
2. See how the TV works with that. If not good, find a good point in between, where the TV looks good, even if the outside is a little bright, like here.
3. Keep your shutter speed below 1/250 sec or 1/200 sec, depending on your camera.
4. Now add flash; add the right amount to match the ambient exposure. Bounce the flash from a point behind you that gives equal brightness through the room.

And that’s all. Not that difficult if you approach it right!