I think the videos I cited (as opposed to the one cited by Andy, which seems to be the 'bone of contention (har!)) might have been a little clearer. IMHO.
On the other hand, I'm interested to know what Mark, Greg and Dan mean by 'elbow power'. It seems it means something else to them?
More info on Elbow Power can be found in this previous thread: http://www.aikiweb.com/forums/showthread.php?t=20105
I am not sure what else can be said other than Elbow Power can mean various things to various people based on the context of how the term is used; and that does not mean others are wrong in their own environment, it just means it is not right for in the context of Aiki. Just to sum up some points for aiki: the concept of elbow power is more than a simple movement of the elbow to get in a better leverage position to effect a throw. There is a mental component that controls internal energy that leads a physically movement; there is whole body connection where when one thing moves, all things move; and there is a union of opposing forces set up by internal spirals where the elbow becomes a point within a whole body spiral that effects anything that connects with the body. As Dan said, it is not just about the elbow, the aiki concept of elbow power can occur in any part of a connected body. Sorry, this may not be the well detailed road map everyone was looking for, but there is just so much going with the concept, that online discussion is pretty much useless, and an in person hands on demo says it all in a few seconds.
Just my opinion, and of course, YMMV