Animating a Nurbs Path's Influence Say you have a spiralling object with an armature rig, which in turn has a Spline IK bone constraint to a nurbs path, as per a tutorial for a bending phone cord.

Now you want to animate the various poses you've made by warping the nurbs path, such that you can import it into Unity.

I've tried adding LocRot keyframes of all the armature's bones in each pose, as well as "Object (or Pose)->Animation->Bake Action"; none of the armature's changes from the Nurbs path's influence come through in any Action clip. Ideally one would just animate the positions of the Nurbs path; alas, Blender doesn't let you add keyframes of individual vertices of anything in Edit Mode.

Some light to shed?
Shape key animation did it. For posterity, you hover over the value slider under the shape key list and hit "I" to insert a frame with that value.

Thanks Jerryno and user2511.