Avisynth is a scripting language and a collection of filters for simple (and not so simple!) non-linear video editing tasks. It frameserves video to applications.
FreeFrame is the open-source cross-platform real-time video effects plugin system for VJ softwares. FreeFrame is now well supported by most major VJ titles. More information on the home page: http://freeframe.sourceforge.net
Glame is targeted to be the GIMP for audio processing. Glame supports non destructive multitrack editing, recording and mixing; realtime effects using native or LADSPA plugins; OSS, ALSA or SGI audio and WAV, Mp3 and Ogg file formats.
SRec is a program for recording videos from whatever is happening on your AmigaOS 4.x computer screen (useful for making tutorials, showing off games/programs, etc.). This is a purely software solution so no extra hardware is needed to use it.