The source code of bitcoin, where i can start, if there video or explain the code is better.
I have a lot of question, like what is the different between coins working in blockchain.
Bitcoin was originally written in C++, looks like satoshi was programing under a windows environment and not linux which was surprising to find out to me.
So for starters, you would need a very high level of C++ to even pretend to start looking at the code.
Once you have adquired an high level of C++, you will need an high level of cryptography to understand the context of what everything is doing and why.
Once you are good in both C++ and cryptography you will be able to look at the code yourself. No amount of youtube videos briefly explaining the code will help if you aren't versed in the programing language used for Bitcoin and cryptography.
You don't need to learn that much about using cryptography, just hashes and digital signaures using the secp256k1 curve.
The wallet is encrypted but that's just a minor detail really as it doesn't have to be.
So you need to learn about the following :
sha256 hashes
ripemd160 hashes
How to create a keypair on the secp256k1 curve
Sign something (I suggest an sha256 hash of something) with an secp256k1 private key and then verify the signature with the public key
Once you know the above that covers pretty much all of the cryptographic primitives used and you can then start looking into how these functions are used inside Bitcoin.
I would suggest downloading a library like libsecp256k1 and writing some test programs do do the above.