How does money move when you write a check, or do an electronic transfer?

When you transfer money to someone, whether it be by check or other electronic transfer the transfer is the same. If you are transferring within the same bank then it is simple. A bank can transfer by decreasing your account balance, and increases the other persons balance, but what if its to a different back or even to a different state or country?
The way this works is Bob sends Bill $10.00, Bob banks with bank A and Bill banks with bank B. Bob goes to bank A and says I want to send $10.00 to Bill, Bank A takes Bobs money, bank A then contacts Bank B and says add $10.00 to Bills account and to take it from Bank A's account with bank B. Easy enough, but what happens when bank A sends too much money to bank B? Remember banks are holding peoples money who may show up at any minute and withdraw their money so the bank must have enough money on hand to at each branch to cover such occasions. So what happens when they have to actually move money?

That's right, money like it or not is paper, (paper that a government promises is valuable), and if you want to move paper from one place to another you have to physically move it. They say Bitcoin is not efficient, how is moving money with these armored cars efficient? Bitcoin and Block Chain are the future. This video below is the best I have seen on this, enjoy.

This is not a FUD video.

Bitcoin, the Final Boom or Bust - Mike Maloney, Clif High, Jeff Berwick