Black background accentuates the mirror effect. I'll give you the screen protector, looks like you left the surrounding window on iBooks or something. It looks like a filter.
If that is your video I just saw where you said it "debunks" the Kindle ad. It really doesn't. Again, the angle of the thing matters. Do another video where the iPad's screen is DIRECTLY angled at the sunlight, because that is how you would hold it if the sun were directly above or just behind you - roughly at a 45 - 60 degree angle. Not a perfect 90 degree angle. That is going to skew your results. You WILL end up with an image that looks similar to the Kindle ad. Now, that guy had his brightness down. But it's still not going to be that much clearer.
Other skews:
- Fingerprints
- Presence or lack of a screen protector of any kind