www: FFmpeg or libav
license: LGPL 2.1, or GPL 2.0 if optional components are selected at FFmpeg/libav build time
optional, remove by deleting #define SUPPORT_FFMPEG and #define SUPPORT_LIBAV in src/LightsprintIO/supported_formats.h (for Linux, remove linking from makefile)
Windows: download precompiled version for example from here, here, or build your own FFmpeg/libav from source code
OSX: install with sudo port install ffmpeg-devel -gpl2 -x11
Ubuntu: install with sudo apt-get install libav ?