Realtime Collaborative Playback Synchronization

Dropbox Replay's Live Review feature enables real-time, synchronized playback for remote teams. This capability has evolved to address the complex challenge of maintaining consistent video playback state across multiple collaborators, even with concurrent user interactions. The system uses WebSockets and Protocol Buffers for communication, with a server-side sync service establishing a logical clock and 'happened-before' relationships to ensure all clients converge on the same playback state. This ensures a smooth and predictable user experience, approximating in-person screening room collaboration.