Hey guys,
I dont know how to do exactly as that video, but i know a way to hack dragon with some millions level (heath and hit point also millions). However it is only available in smart phone.
Here is my guide for your reference, but game will not be fun any more:
using Vutrans 's Multi-tool
move any your storage egg to any habitas, your dragon level some time will be "zero" but when you login by phone, it will be million. Let ur trying.