Inside Facebook’s video delivery system

What this post added

This post details Meta's extensive two-year effort to unify its video delivery systems, consolidating the previously separate Watch and Reels products and their underlying infrastructure. It outlines the three core systems involved (ranking, server, and mobile), the strategic reasons for unification (fragmented user/developer experience, creator overhead), and the complex technical challenges overcome in merging client and server data models, architectures, and ranking layers. The post also describes the lifecycle of a video feed network request and highlights key principles guiding their video delivery system.