|Did you read the answers? :)|
"How do I set up video calling?
Before you can call your friends, you need to complete a quick, one-time setup:
1. You will be asked to complete the setup the first time you try to call a friend, or the first time a friend tries to call you. To call a friend, click the video icon at the top of your chat window.
2. Simply click the “Set Up” button and follow the instructions for how to set up video calling on your browser.
3. Once you’ve successfully completed the setup, the call you’ve started with your friend should connect automatically. If it doesn’t, you can call again by clicking the video icon at the top of your chat window."