This happens commonly during Video Call through FaceTime on many users, especially the one who have just upgraded iOS 9. The errors:
- You can see the others, but they can not see you (You still can see your self at the conner).
- The called friends can see you, but what you see is only an image of them on the screen.
- No video while voice seem to be transmitted well from both sides.
How to fix?
After a while chatting with Apple support, this works on me:
- Check the date and time if they are not set correctly.
- Reset Networking setting (Settings > General > Reset > Reset Network Settings) then Reboot the device (iPhone or iPad).
- After reboot, add Google DNS (18.104.22.168, 22.214.171.124) to your network setting.
I do not know why but after all above, the problem is solved on me.