Making a digital video of a software architect explaining a system to another developer/architect may help to document the intention behind a system.
I was listening to an IT Conversation with Alistair Cockburn: Agile Software Development from 2004 and he talked about this idea (amongst other things). The main discussion is about how much documentation you should do in an Agile development. The answer 'enough to be useful' is alright, but a bit nebulous. I want documentation to assist my understanding of what the system does and is supposed to do. Documentation encompasses design documents, UML diagrams, etc. and when the system has been coded: code comments…which are useless unless kept up to date, maybe they should be banned and developers forced to write their programs in a logical enough way that it is obvious what each individual subroutine is intended to achieve…unit tests, as in my opinion they should not only prove that the software works, but they demonstrate what should happen when the routines are 'exercised' [is this an original term?]….
Anyway, the idea Alistair Cockburn mentioned was to do a form of peer review where you video the system designer explaining the system to someone from another project. The visitor's questions will hopefully include the one's that new developers would want to ask. This will help to record the original intentions of the system.