Sketch of how the exhibition setup could look like (only schematic) if I only use one Leap Motion. The iMac would process the incoming data from the Leap device and would display some visual feedback on one projector.
It would also play the interface sounds directly (usb audio interface would be needed for that, because headphones will also be attached to the iMac playing the sound of the concept video).
For the text assistant and the music sound, it would send shiftr commands to the MacBook, which plays back the music. At the same time it will display the different assistants of the three objects on the second projector.