How can you guarantee it is not 25%? Did you read the Airbus information?
No, I didn't read the Airbus propaganda, but I do know this:
Boeing has been building jetliners for 60 years without windows (except for the flight deck and exit portals) - KC-135, 747F, 757F, 767F, 777F. Their fuselage structure is optimized for the lack of windows. Yes, it saves, weight, but the number is small single digits (the previous post quoting 200kg for 150 seater is ballpark). Once you add in a couple large view screens for each row, plus cameras, associated wiring and controls, it's probably close to a push.