How data is protected on canister (cancan specifically)? and some other basic questions

I appreciate it if someone can answer any of the below question:

1- I browsesd documentations and codes but could find the answer to this question.
In CanCan, when a video is saved, is it encrypted in some way? I could not find where this happens in the codes, anyone can guide me? Is it something that happens on canister level automatically?

2- Is there a specific reason in CanCan files is saved in [Nat8] instead of blob?

3- What is the difference(and usecase) for StateShared vs State? I know it says one is stable, the other is not, but I did not find any stable keyword or difference between both