I tried it on Android, I don't think it is that sensitive or polling right. I was able to determine hand movements causes it to think flicker is occurring the more exaggerated the movement, the higher the flicker, so really it needs to be placed on a stable surface and not held at all.
I question some of the numbers too.. it was reporting 2% flicker on a T12 CCFL that has an electronic ballast at 20 kHz. I don't know that this number is accurate for my phone camera.
I took it to a closet that has a single incandescent bulb which has a current flicker of 120 Hz but due to blackbody effects it is not on and off like LEDs are. On the top shelf closest to it, it was reporting 2% flicker. Moving it to a lower shelf where there was less light but still the same bulb, it reported 5%.
I don't think a phone camera is capable of being a measuring instrument for this sort of thing.