Broken version, was at: http://www.youtube.com/watch?feature=player_embedded&v=mVHgJFrBvC0
From the narrator (?):
"Uploaded by cwm9 on Dec 3, 2011
The coordinate system or Revit has been rehashed many times on blogs and posts, but has been clear as mud for me, and I suspect a lot of other people. So I took the time to really figure out it, and here's a 30 minute explanation of how Revit's coordinate systems work, interrelate,
how true north works, and how to put multiple copies of a building on a site."