What's the difference between stg-extensions.sketchup.com and extensions.sketchup.com?

Extension Warehouse
1

Continuing the discussion from SketchUp MEP for free?:

In the above linked post, there is a link to the Trimble MEPDesigner for Sketchup. It links to:

https://stg-extensions.sketchup.com/en/content/trimble-mepdesigner-sketchup

When I follow the link, it appears to be the extension warehouse, but I can’t login - and login is needed in order to view the 3 videos - which I want to watch!

From with Sketchup, using the Extension Warehouse window, searching on “MEPdesigner” fails. And the window shows that I AM logged in.

Back in my normal browser, going to:

http://extensions.sketchup.com/

also shows me as logged in, and also fails to find anything when I search on “MEPdesigner”.

So is “stg-extensions(dot)sketchup(dot)com” different from “extensions(dot)sketchup(dot)com?”

Or to get to what I really want to do:
How can I view the 3 videos I see at:
https://stg-extensions.sketchup.com/en/content/trimble-mepdesigner-sketchup
???

2

I went back and edited my response in the other thread. That is an old link. The extension is no longer availabe.

3

That explains things. Must admit a bit of disappointment as I was looking forward to perhaps using it - based on the videos I was unable to see!