I tried everything to solve this problem including contacting AppleCare Telephone Support (who had me resetting network settings) and my ISP (who checked out my router and tweaked a few settings) but all to no avail. Then along came a software update (9.2) and as if by magic my granddaughter can see me again! I haven’t tried anyone else yet but I guess the problem has gone away, at least as far as I’m concerned. There seems to have been no admission from Apple that this problem ever existed and it’s not referenced in the list of bug fixes – though there is “Fixing an issue where Camera screen on iPad could be black when attempting to capture video” which could possibly be relevant. It’s so annoying not to know!!! Hope everyone who suffered from this problem (which wasn’t all iPad FaceTime users – why?) finds it’s now fixed.