У вашего броузера проблема в совместимости с HTML5
Using custom mob spawners, I made an animation of a tree growing.
World download: https://www.dropbox.com/s/7uguttpg81jiawh/3danimation.zip?dl=1
Filter download: https://www.dropbox.com/s/zdbzq5vhfy31des/animator.py?dl=1
Video showing how the spawners spawn the structure: http://www.youtube.com/watch?v=sMZGOu3VmAY
Music at the end is Cipher by Kevin MacLeod