I touched on this in your other post. Here it is again.
In the Engine Manager there is "VOD" and "VOD edge" application types which use the same stream type. The only difference is one gets configured for MediaCache and the other does not.
There is not really such a thing as a "VOD Origin". MediaCache is the VOD equivalent to a Live Stream Repeater. But there is not a VOD origin. In this case, the "VOD origin" would be the storage location, not another Wowza server.