No, i’m not asking for an entire code, i just need to understand How the code works/ what is the code doing. Here is the video:
What i think they did:
The model is playing an animation while the whole group moves into different transparent parts.
This would only require to make the model move to a certain part while the animation makes the illusion
Other ideas:
There’s no animation, it’s all well-written cframe code that gives the illusion of the model’s parts being all connected. This one would be the hardest one to make, as they would not have the help of an animation editor, but would only have to use numbers FOR EACH PART.
It’s all an animation for a rig, including the movement. This would explain the unstable and constantly changing speed of the caterpillar.
This one would be the easier one to do, however, Rigs have the problem of not being solid parts, and even the player decides to touch the caterpillar, it would move. This would only require a simple script to make the rig play an animation
If you have any idea of how they coded it, please let me know! 
Thanks for reading.