Win10: How to display art on second display with lock screen activated?

My displays are always on, and I like to have artwork on them.

But when the screen is locked, only the primary display shows anything.

How do I:

a) Get the OS to push an image to second and/or third displays when the console is locked?

b) Control which image (or mp4) is looped to that display?

Since Windows 10, Microsoft has disabled multi-monitor lock screens. So you need third-party software for that. Under Windows, the lock-screen will display on the main monitor, while the others will be blank.

Try for example DisplayFusion, although the Pro version might be needed.

Other possibilities are Dual Monitor Tools, UltraMon or Stardock.