Dave Phillips has made AVSynthesis working on Linux. This is not a trivial task as AVSynthesis is using third party libraries, like LWJGL and Csound. Great job Dave!
He has also produced some video demos that sounds great at http://linux-sound.org/avs-examples/
Here is a thread in the Linux audio mailing list http://lists.linuxaudio.org/pipermail/linux-audio-user/2007-December/049803.html