This finding is amazing and doesn't fit only newbies. It fits me as well. I know most of the way BTC works but some in-detail stuff this simulator explains that I've missed is simple to understand and widens your existent knowledge.
Yes! I was also surprised when I encountered this website, it actually shed some light on the vagueness of the bitcoin protocol. And now I understand the basic concept, it should be easy to dive into a more technical side of bitcoin.
I didn't understand the calculation aspect that is related to private keys. How we can find out that Person A is not fake claiming to be Person C I think its a feature that the bank use to beat bitcoin.
It's the
Digital Signature.
It actually has the resemblance of how the banking system works. In order for someone to transfer money from point A to point B, the bank will request a handwritten
signature that will verify the legitimacy of the sender. It is the same on how bitcoin transaction works but the difference is, instead of the handwritten signature, we are going to produce
digital signature as a verification for the sender using the
private key and the
transaction (recipient address, amount of
BTC to be transferred.)
transaction +
priv_key =
digital_sig => means that you sign the tx using your priv_key without exposing it to the public. Your tx is now ready to be published in the bitcoin network.
digital_sig +
pub_key =
transaction (substitution)
digital_sig =
transaction +
priv_keytransaction +
priv_key +
pub_key =
transaction In order to prove the legitimacy of the sender, the
priv_key and pub_key pair should be match.
. 
Watch the video first or read the tutorial if you don't know about it. 
