Why do credits on shows/movies flutter/pixelate?

[candcgregory]

For about the last year or so, whenever I watch a show or movie on FIOS, and the end credits roll, the typography "flutters". The type goes from being clear as a bell to a pixelated mess, and back. It doesn't matter what channel-EPIX, HBO, Cinemax, Starz, Showtime. It's maddening, and I can't find this issue online anywhere else. 

I watched ep 2 of Ray Donavan season 3 last night, and as soon as the credits pop up, same issue. Tonight, I watched Capote, which I'd taped to my DVR a year ago when it played on EPIX. I don't notice it anywhere else within the movies or shows, but it's still an annoyance. 

All the connections are tight. Subtitles are fine. Network diagnostic from the STB shows the signal is fine. I've reset the STB, and nothing works. The issue doesn't happen when watching content on HBO Go, or Showtime Anytime through my Roku, or anything from my Bluray player. 

Suggestions? Is this an issue with the stream quality? 

[sangs1]

Don't know why it happens, but can confirm I experience it too. Only on credits with black screen and white print though. Doesn't happen with our DirecTV feed, so it's obviously something on FiOS. Maybe some sort of transcoding glitch. Anyway, I've learned to ignore it, since it doesn't happen any other time.

[tns2]

Always been a common problem that the credits do this.  Was happening way before FIOS or even cable TV.  Some networks even took to replacing original credits with there own digital versions to avoid this.  Has to do with very sharp edges scrolling.