yt-dlp is a feature-rich command-line video/audio downloader, forked from youtube-dl. It extracts media URLs from over a thousand websites using site-specific extractors, downloads via HTTP, HLS, DASH, RTMP, and other protocols, and supports extensive post-processing (FFmpeg transcoding, metadata embedding, chapter manipulation, etc.). The architecture is modular: a core engine (YoutubeDL) orchestrates extractors, downloaders, and postprocessors, all of which can be extended via a plugin system. Networking is abstracted behind a handler interface with support for requests, curl-cffi, and websockets. The codebase is well-structured, with clear patterns for authentication, geo-restriction handling, and format selection. It includes a sophisticated JavaScript challenge solver and Proof-of-Origin token system for YouTube. Despite its size, the project maintains good code organization and extensive test coverage.