This is using Sforzando to change to different chord sections instantly.
The chord is input via keyboard/pad.
This is the same way it can work with Biab using the BBPlugin Standalone.
The user selects the Style and tempo and the track data for all instruments are loaded in.
It's using the same chord detection as Biab and simply plays that chord sample section from within any number of source wma/wav files.
The demo has not got sync beats change in it as they still have to implement that in Sforzando to change from chord to chord in sync on beat and smoothly.
This shows it can be done, so a Live Arranger version of Biab is possible.

Watch: https://www.dropbox.com/s/4sdl87ge4y9y5kc/Sforzando-Arranger.mp4?dl=0