Nimbuzz is the free call and messaging app for mobile devices and they have not launched a new service which allows you to do video calling from iPhone or iPad (using iPhone app) to Windows PC. You can make free video calls between iPhone and PC once you have installed the application on both the devices. The Nimbuzz video calling feature works over 3G/4G and WiFi, so no matter where you are you can always connect with your friends. All you need to do is make sure that both you and your Nimbuzz friend have installed the latest version of the app to enable video calling.
When you click on the Video call button on the chat window, your free call is connected to your friend using iPhone.
On your iPhone or iPad, you can use either the back camera or front facing camera. To set up video chat from iPhone to PC or vice versa, download the apps for the respective platforms.