It would be a welcome addition for video panels giving live control for their brightness.
This would make it much easier to simulate different stage looks with video elements without having to connect to an actual media server.
Also I have been trying a spark machine model which someone had adapted from a flame projector model by Marco.
The original version (opengl) worked by using videos of the flames/sparks on a 100% transparent material and placing lights within the model which still worked on any non-black parts of the video. A nice effect and control is simulated by dimming the lights.
It does not work this way in the current directx version, the lights no longer work on the non-black material at 100% transparency.
However, turning on luminance for the material does work nicely. Having dmx control of the luminance would allow live simulation of controlling the flame/spark machine. (I have also played with trying to emulate the spark effect with the water jet fixture and can get an interesting effect but that too needs a luminance control to create the desired effect, I see you have already added my request for that to be expanded to the list, thank you)
I guess you might want to set a luminance range (there might be instances where a minimum level is as useful as a maximum) in the materials properties and have dmx control scaled to it..