This tutorial guides developers on how to use Agora's Video SDK to build a cross-platform video chatting app. The app supports four major platforms - MacOS, Windows, iOS, and Android. It focuses on creating a simple 1-to-1 video chat scenario using Unity Editor. The tutorial covers setting up a new project, importing the Agora Video SDK for Unity, creating user interfaces, developing a controller script, setting up UIs, handling Agora Engine events, and testing the code. It also provides tips on application clean-up to prevent memory leaks and resource mismanagement. The completed project can be found in this Github repo.