Has anyone figured out .nodes files?

[Cranky Old Man]

This is my guess:
The monster will of course choose the path to the player that has the least distance. By lowering the distance values between two nodes, you can made the monster prefer this path. For instance, if the player is hiding on the other side of a spike pit, you can set the distance leading over the pit to be really long. In that way the monster will percieve the paths leading around the pit to be shorter, and take that path instead. Only if those paths are blocked off, will the monster try to cross the spike trap.