As I stated in my previous (multimonitor bug report) post above, Deskscapes works fine for me.
Here's my working setup:
Windows 10 Pro x64 (in place upgrade from Windows 7 Pro x64)
DeskScapes v8.21 (all default settings, except "enable support for additional graphics cards" is OFF, as I only have one card in this rig)
Shark007 Advanced Codec Pack for x64 (no idea if this is needed for the Video 'scapes or if this is just legacy)
PhotoDream on Primary Monitor
GoodNight Earth and Utopia video dreams on Monitors 2 & 3. All monitors 2560x1600 on Nvidia 970 card. Extended desktop configuration. Latest Windows 10 drivers.
Is there any information here that helps anyone get this working on their end?
Either way, I hope it helps, good luck.