For the time being, Android users are receiving the new feature if you have the latest update or if you have any of the latest betas.
If the person you are calling doesn't yet have the feature, the call will be converted to a voice call on their end.
For those that are desperate to get the update before their time, it appears that if you wipe the app data and log in again fresh, it helps with getting the video calling working.
Source:
AP
Written by: Andre Yoskowitz @ 25 Oct 2016 20:28