The tutorial explains how to build a video chat app using React Native with the Vonage Video API and Opentok React Native library. It covers setting up the project, building the video chat interface, adding participant streams, building the video call toolbar, and optimizing the app for multiple streams. The app is designed to handle different use cases, such as displaying a main subscriber view and a scroll view component with smaller thumbnails for remaining subscribers. The tutorial also includes best practices for handling group calls on mobile devices and optimizing performance by muting non-visible stream videos.