Viber has declared that its calls and chats are end to end encrypted that allows no recording of the calls from the app side. It Assured that people do remains properly secured and not allows some other person to interfere.
It offers the end to end encryption system. It is the high tech security that prevents the entire chat and gossips through video calls. It means one can confidently contact with fellows and have conference calls with the employees without fear that they lose their privacy.
So, if you are concerned that your video call gets leaked through Viber then it will not happen and you can communicate with confidence with your team members.