That's a flawed analysis because burn-in can occur whether the light is direct or reflected. Old rear projection tvs used a mirror to reflect light too and they suffered burn-in as well. It all depends on how intense the light is and how durable the screen is. In fact rear projection DLP have very shallow cabinets so the light doesn't have to travel very far thus it still retains the high intensity energy at the screen.
You can do a very simple experiment to see what actually happens. For example take a very clear mirror and reflect the sunlight onto your skin and you'll be able to feel the heat very quickly. This heat will eventually cause burn-in on a screen with a static image even though the light is reflected and not direct. I say urban legend.
You can do a very simple experiment to see what actually happens. For example take a very clear mirror and reflect the sunlight onto your skin and you'll be able to feel the heat very quickly. This heat will eventually cause burn-in on a screen with a static image even though the light is reflected and not direct. I say urban legend.