let me show you how to do that with OSC and one of the new Materials that come with MM 2.5 and apply it to all surfaces
Open the Control List menu Controls/Contols List
select the osc tab press + to select the appropriate media and the apply_to_all_surfaces control
and then define the osc adress on which you want to send to actually apply the media to all surfaces
Now if you send a value through OSC on this channel it will work.
This works for keyboard, midi, etc... pretty useful i agree