I'm seeing the same issue.  Near as I can tell, the Stellar Forge does nothing.  Doesn't increase HP or lower maintenance.

I am unable to duplicate your success with the Stellar Forge.  It doesn't work for me.  I am convinced we have differing versions of the game, but dam-if-I-know how.  I base this reasoning on the fact that the Stellar Forge displayed in your video shows +10% Hit points AND +10% maintenance reduction even with zero adjacency bonuses.  The version in my game does not show maintenance reductions until it receives adjacency bonuses.

Steps Taken:

• Using Steam, delete local copy
• Cleanse My Documents of Mod content
• Reinstall game via Steam
• Launch, test using cheat codes, still broken
• Scratch head, go back to Steam enable opt_in_update
• Launch, test using cheat codes, still broken
• Scratch head, come back to forums again
• Using Steam, delete local copy (I have a very fast internet connection so WTH)
• Check steamapps directory, GalCivIII folder still present due to some modded files from Gauntlet's Racial Mods.  Fry these files.
• Reinstall game via Steam
• Test etc ... still nada.  My version of the building is still different from yours.  WTH.
• For what it's worth, my version of the executable is "1.6.1.3"
• I switched around between v1.61, vip-build and the optn_in_build, with none of those do I see a working Stellar Forge.

Ok     i verified game files on steam, it refreshed several files, now my forge does nothing, no idea.  very strange

Thanks for the report, found the issue and will have it fixed in the next patch.