The article explains how to add CSS filters to a video application using React and Twilio Video. It starts by cloning a repository, configuring credentials, and running the app, then adds a set of CSS classes to apply different filters such as sepia, invert, grayscale, saturation, and blur. Two new React components are introduced: FilterList and Filter, which create and hold the filter options in a list, allowing users to select a filter. The article also covers how to communicate the selected filter between clients using Socket.io, enabling real-time updates across browsers.