Media Downloader is a cross-platform Qt/C++ desktop application that serves as a graphical frontend for multiple command-line download tools (yt-dlp, gallery-dl, aria2c, wget, etc.). It provides a tabbed interface for single URL downloads, batch processing, playlist and subscription management, and a library browser for managing downloaded files. The application manages the lifecycle of external engine executables, including automatic download and updates, and supports proxy configuration, themes, translations (17+ languages), system tray integration, and extensive download options (format selection, subtitles, chapters, etc.). The architecture follows a plugin-like pattern where each backend engine is wrapped in a polymorphic class derived from a base engine, with JSON configuration files defining executables and options. The code shows strong engineering discipline with clear separation of utilities, engine wrappers, and UI components, though some files (e.g., batchdownloader.cpp) are very large.