ep 13: How is bitcoin "locked" to an address - OP_CHECKSIG, locking scripts, signatures, UTXO chain

I've been meaning to make this video for a long time. It follows on from episode 12 which talks about locking and unlocking scripts and here we finish off the explanation with a look into how digital signatures are used to ensure that only the intended recipient of UTXO (unspent transaction output) can actually spend that UTXO in new transactions. Essentially the transaction is defined and then hashed and that hash is encrypted with the private key of the transaction creator (spender) - that becomes a signature of the transaction - and is used by all the nodes in the network to validate the transaction, and ensure that corresponding public key is the one used as the beneficiary of the output referenced in the transaction inputs.