A makehuman character shakes his head and loses his teeth.

I imported the "collada" file from makehuman character into blender. I parented the provided armature to the mesh. I thought I was basically following the advice from this blenderartists posting. This is the result. I cannot understand why some of the vertex groups-- but not ALL of them-- choose to disobey the parenting. Any tips?

Addendum. Okay, I wasn't following the advice perfectly. They say to make the teeth into a separate object. But I still thought it would be fun to share this video.