I guess in the video there is two context, the default Revit context and new Addin context.
By default Revit always creates the IExternalCommand in the default context. And that command finds the new Addin context already created in the IExternalApplication to re-execute the IExternalCommand in the correct context with all the dependencies loaded in there. The idea is to only use the new Addin context, I suppose you are doing some similar.
@mike.olearyZ8X6J wrote:
And finally, yes I agree, it would have been much more ideal if Revit were loading the addins in a separate context as this would avoid a lot of headache for developers, and in my opinion should have been done as part of the .net core support being added.
Yes, Autodesk missed the opportunity to launch in Revit 2025, maybe next version happen. There is something in the Revit Preview.
I already tested, and I can't discuss outside Revit Preview forum. If you want to know how that is working follow the link.