The sequences in this video were rendered using the newly released open-source Away3DLite. With 484 cubes and well over 5000 faces, the spectrum calculations and transparencies, the new engine manages to render smoothly. The compiled swf is 28kb!

You can view samples of live rendering on my site at:
wemakedotcoms.com/_exp/soundSpectrum/3D/v1/SoundSpectrumDisplay3D.html and wemakedotcoms.com/_exp/soundSpectrum/3D/v2/SoundSpectrumDisplay3D.html

This is a Flash Builder 4 AS3 Project targeting Flash Player 10.

The audio track used is Glitt by Vasculoid
opsound.org/artist/vasculoid/