Funny that you should post this, as I meant to post something about it, too recently . . . .

I was chatting with a FA about the B763 refurb, and mentioned that someone was taking FLASH PICTURES throughout the flight, and how rude I thought it was! I told her that I couldn't see who was doing it!

She told me that it's a known glitch of some sort, in the refurb! Amazing!