I think you can do it with MC12 and your laptop and multiple zones and you won't need anything else more fancy. I run similar setups regularly and it works great with the new Detached display setup in MC12. Takes a little fancy finger-work on the MC UI, but practice makes perfect.
Do this:
1. Set up your laptop with the Projector. Once you're all set up and booted up into Windows, you'll want to enable "Extended Desktop" mode (rather than Clone mode). To do this:
a) Right click on the desktop and choose Properties. Switch to the Settings tab.
b) Click the Identify button to figure out which display is which. If the laptop's screen is NOT #1, then select the #1 icon in the big empty area, make sure Use this device as the primary monitor is checked (it really should already be #1 but just in case).
c) Click on #2 in the empty area in the dialog, and check "Extend my Windows desktop onto this monitor".
d) If you want, you can arrange the monitor and projector into a different orientation. For example, if you drag-drop #2 above #1, then moving your mouse up past the top of the laptop's screen will move the mouse onto the bottom of the Projector's screen.
2. In MC12, go to Player --> Playback Options --> Zone Manager. Create a new zone, but leave the settings alone. Close the Zone Manager.
3. Position MC12's interface on the laptop's screen. Make sure Zone 1 is chosen. Change the zone's Volume type to Internal. (This is so you can control the volume of the Audio separately from the Video running in Zone 2). Start some music playing and pull up your visualizer (G-Force works good).
4. Right click on the display and choose Detach Display. Move this to the projector's screen and double click (to send it full screen). It should happily play G-Force (or whatever) nice and full screen on the projector for you.
5. Switch to Zone 2.
6. Change Zone 2's Volume Type to Internal as well. Start a video playing. Switch to Playing Now (if it didn't do it for you).
7. Right click in the Playing Now display area and choose Display settings. Make sure the Full Screen monitor setting is Nearest Monitor. Close that dialog and right-click and choose Detach Display. Move this display over to the Projectors screen and double click it to send it full screen.
8. Now, when you don't want the projector to show the movie full screen anymore, don't double click or hit escape to "un-maximize" it -- instead simply click in the Playing Now area (or the Display Action Window) where it says "Display is detached. Click here to bring it back." That way, next time you start a video and detach the display, it will remember that it was both full screen and on the Projector and just go there automatically (and "cover up" the playing Audio visualization). The goal is to get this all set up ahead of time, and then once you start the "show", don't ever move your mouse over onto the Projector's part of the screen. Stay within the confines of the MC UI on your laptop's screen and all should be good.
If you want the music to just keep playing through the video (this is what I usually want when I set up similar shows), you don't have to do anything -- just run it. If you want the audio to mute on the music, you'll need to manually switch to Zone 1 and volume down before you start the video.
You can manage the playing now list and pick and choose your video files through the regular MC12 UI on your laptop's screen all "behind the scenes" and no one will see what you're up to.
The only downside to this method at all is that your video will start playing before you detach it. As soon as you detach it, it will show up on the projector, but you have to be ready. I solve this by simply adding a few second black/silent header to the video files I'm going to use for this purpose. If you can't do this, just be quick. You can also start the video, pause it immediately, then switch to Zone 1 (the Music Zone) volume down, switch back to Zone 2, detach the display (which will send it full screen to the Projector), then un-Pause.