Unfortunately Anim8or cannot do this (yet). There are, however, a couple of possible workarounds. For example, to replicate the attached video, you could render the entire scene twice, once with a red ball, and again with the material changed to blue, then use video editing software to fade from one video to the other. Alternatively, you might be able to achieve a similar effect using a white ball, being illuminated by a light (or set of lights) that changes colour (which can be animated). You cannot define which objects are affected by which lights in Anim8or like you can in some other packages, so the lights will affect all the elements in the scene, but perhaps with careful placement, aiming and light range settings you might have some luck. I am sure there other workarounds as well, but direct animated transition of material elements cannot be done with Anim8or at the moment, unfortunately.
NOTE: I think Terranim8or has some functionality in this area, it might be worth investigating.
