MoviePy is a Python module for video editing, which can be used for basic operations (like cuts, concatenations, title insertions), video compositing (a.k.a. non-linear editing), video processing, or to create advanced effects. It can read and write the most common video formats, including GIF.
Audio and Video
Some Python-based projects related to audio and video. See also Screencasting.
Jokosher - a complete application for recording, editing, mixing and exporting audio
See also PythonInMusic for more projects.
FUPlayer - a music player with management and CD ripping/burning capabilities
Listen - an audio player with music management features
Quod Libet - an audio player with scalable management of music collections (more than "a mere 10000 songs")
TimPlayer - a PyGTK based music player using GStreamer (see http://creationix.com/OpenSource/TimPlayer/)
Libraries and Frameworks
GStreamer - an audio/video playback framework - has Python bindings
MLT - an open source multimedia framework, designed and developed for television broadcasting - has Python bindings
MoviePy - a Python library for script-based movie editing (cuts, concatenations, text insertion, non-linear editing)
See also Audio for details of Python audio libraries.
Elisa - an open source cross-platform media centre solution
Freevo - Linux multimedia jukebox
Boxtream - a mobile and autonomous audio and video streaming and recording studio (uses GStreamer)
Flumotion - a streaming media server (uses GStreamer)
OpenShot - an open source video editor, written in Python and based on MLT and PyGtk
Pitivi - an open source video editor, written in Python and based on GStreamer and GTK+