The rigs and items were made by TheAusFinn. He said that he wants to finish some more things before making them public. He does have his first rig on this site here:http://www.moddb.com/games/minecraft/downloads/3ds-max-minecraft-human-model-rigged-v05
As for tips and getting smooth movement. Just try contrasting between fast and slow transitions. I’m still getting new to it, I only have been animating for a few months since I started. I was mostly into motion graphics before 3D animation.
If you go to videocopilot: http://www.videocopilot.net/tutorials/
There are some tutorials in composting 3D objects on real footage. Check his tutorials relating to creating a meteor and a crater. Number 72