Material Changing in an Animation!

I was wondering if it was possible to alter a models mesh whilst in an animation so I had a search on the internet and found this video [LINK]. Whilst playing with this tool I was surprised by the simplicity to pull this effect off. The only real weakness I found was rendering time had increased massively. I'm not sure if this was an issue with my computer so I'll have to check it on the university computer when I am next in. I was trying to build a scene of an ice age and the planet Earth heating up but alas rendering was so poor I opted out for an image. It gives a general gist for what the tool can accomplish.

The menu screen to the right is where the magic happens. By moving the line on the bottom graph whilst Auto Key is active allows you to change the intensity of one image as time goes by creating the effect in this case of Earth heating up and ice melting.