I have the same issue with my Mother in Laws iPad.
Worked fine for 19 months, she did the update but now anyone she face times they only get the sound and not the video.
What I have worked out though is this...
If she uses it at my house it works perfectly
I we use our iPad mini at her house it works
If we use our iPhone at her house it works
Its only when she uses the large iPad that there is a problem.
I am convinced that there is no longer enough bandwidth on her upload connection to make it work, because her iPad works on my connection which is better, our iPad mini works at her house as does the phone. So I think that there has been some software tweak that only applies to the iPad and not the phone or mini
Her upload speed is only .85 Mbps, where as I am on 11 Mbps.
So were now stuck with a device that has worked perfectly for 15 months and now after one upgrade has been rendered useless, as its primary function was to keep in touch with family abroad using Face time. We even bought the relatives abroad an iPad for this feature!
Anyone, out there got any suggestions?????????????