Thanks for the links. I actually found and copied over those very movies just before your reply. For the most part, they look great. The dithering is still noticeable in certain shots (dark clouds in the sky, some of the darker shots in the Tron trailer), but it's not terrible. My guess is that it's a screen limitation and that I'm perhaps looking a little too closely.
I don't notice the effect on my iPad with the same movies, but it's not a deal breaker. The flickering worries me a little more, but I'll wait it out and see if anyone mentions it as well. There's a user on the B&N forum asking about it, but no one seems to have a response.