To use the 3D Visualizer to follow a DMX stream from a controller, you have to setup the DMX. You can do this in the 'Show Control' menu, which looks something like this (depending on which version of MSD you have.
DMX mode
With this entry you can switch the follow mode on and off, which you can also do by clicking on the DXM status area in the status bar, which shows the current status of the follow mode with either an OFF 
indicator or an ON 
/ 
/ 
indicator.
Source selection
Here you can select which source you want to follow.
Select DMX Connection
This entry allows you to setup the External source. Selecting this option will open a dialog where you can select one of the installed external drivers, and to configure it using the 'Setup' button, if available.
