Though BBM video calling feature has been around since April this year, 2016 but only for users across UK, Canada and US. The news now is that, BBM video calling feature is now in Africa and some other countries. When you tap the icon to make a call with one of your BBM contacts, you will get a prompt asking if you want to make a voice call or a video call with the beta feature only if your contact is also using the latest version of BBM.
You can now make video calls on BBM using your Android or iOS devices. Though BB10 users has been enjoying this feature long before now. So Blackberry is here to give Android and iOS users a chance to use this feature too. Don't forget that there are still Messenger apps out there that offers Video calls feature which are IMO, Skype, Facebook, Hangout etc.
Android: OS 4.4 (KitKat) and higher iOS: iOS 8 and higher
NOTE: this new feature is only available in it latest version, so please if you haven't upgrade yours kindly do so to enjoy this amazing feature!