Very possible and easy too. 

Look in you're examples there is an example of a frog changing color. And more.
Also you have some animated materials wich comes with Vue.

Doing it yourself is easy also:

1. choose a material at time zero
2. Change timeline to the point you want the new material to be seen
3. Choose new material at the new time. (If prompted "animate material" click YES.

Now you get a gradually changing over time frm the old material to the new.
This is the quick and dirty way.  But there is many more possible.

(PS I still think you had youre materials at "world standard" in youre animation, so when you move an object, the material stays at the coördination, so it looks like its animated, but i could be wrong ;-)