This warning occurs when WATCHOUT thinks that the Virtual Display (the rectangle in the stage window) is overlapping with a cue using it's corresponding media. Such case may result in unexpected graphical artifacts, and that is why you get the warning message.
The cue in this case is the .OBJ 3D object, which is using the image from the virtual display as texture.
There are 2 ways to fix this:
Move the 3D objects further away from the virtual displays, or vice versa, to make sure they are not ovelapping. Place the virtual displays on a different stage tier, and make sure that the 3D object cues are not visible on that tier.
I hope this helps.