Like its last update which allows for tagging group members, there is not much publicity about this latest feature.
The update is not yet available on Google Play Store and only users on the WhatsApp Beta app can access it. On WhatsApp beta tester, sample users can test the newest development of a product before it is deployed onto a larger audience.
For users on the beta, the video call icon appears next to every contact on their list. However, if the other contact is not on the beta app, the video call manifests on the other end as a voice call.