In general, you arent supposed to record in businesses in japan without permission.
Its just that in japan, getting permission is usually considered a hassle for streamers who are constantly uploading content or in japan for a limited amount of time and did not ask in advance, so people follow the record but if you get in trouble, apologize profusely method.
The only thing i find off about the idea is essentially the project is effectively using a different backlight (using a different backlight isnt a completely new idea, its for instance what powers ibuypowers project snowblind pc cases(lcd sidepanel) as it replaces the backlight with internal pc conponents that shine bright white.
If you wanted to fix the problem, would it not just make more sense to put time and effort designing a better backlight for lcds for this use case rather than to rely on a top shot ambient light to do it?