The tutorial expands on a basic WebRTC video chat application by introducing group chat functionality and additional features such as making and ending calls, thumbnail streams for self-viewing, muting calls, pausing video, and handling group chats. It utilizes a wrapper class with the PubNub WebRTC SDK and SDK Wrapper libraries to simplify placing calls and managing user interactions. The guide includes detailed steps for setting up HTML and JavaScript components, handling incoming calls with publish and subscribe keys, and implementing call-related functions like login, makeCall, end, mute, and pause. To test the application locally, it advises setting up a simple server using Python to avoid CORS errors. Customization is encouraged, offering options like appending images when a user mutes their mic or changing video elements when streaming is paused.