Ok, i have tried a few things to make windows dreamscene show along with blackbox.
1. Disable bb's wallpaper options. (achieved through bb's menus)
Result: One Frame of the video is displayed/decoded, or video was treated like an image <- most likely
2. Numerous 3rd party applications that draw windows wallpaper.
Result: most worked while bb was not running, but not while bb running.
Notes: some of these garbage apps (lol) draw the desktop on a different, or the same layer as windows. many are capable of replacing windows's ability to draw wallpaper/video.
2b. remove bsetroot & bsetBG from equation. (Rename to bsetroot.exe2 & bsetBG.exe2)
Results: No notable change with / without changes to bb's configuration concerning wallpaper.
Concussion:
I believe it would be possible to do this with vlc, and a simple plugin that accesses the cli specifically. most windows machines are capable of using --video-wallpaper option. im not a programmer, but i would certainly test this for you.
Another option would be to release a build with the wallpaper code disabled... unless this is a part of the core api.
Final thoughts:
the entire purpose of this experiment of mine, was to build an extremely simple UI for small children. Kids like flash... we all know. (Potential additional usage {track mouse movement, and use coords to update a script that controls wallpaper, kinda like a bubble around the pointer}; though this might be very cpu/gpu intensive. Decrease sample rates Or size of effect/effected area to draw?).