Maths behind Diffie Hellman key exchange

Beautiful 4 and 2 minute videos, hopefully it helps someone who wants to understand maths behind how keys are exchanges on public networks securely (if you use https:// for payments, this maths is used by your browser/app.)

https://www.khanacademy.org/computing/computer-science/cryptography/modern-crypt/v/discrete-logarithm-problem

https://www.khanacademy.org/computing/computer-science/cryptography/modern-crypt/v/diffie-hellman-key-exchange-part-2

At the end of the video you should understand what is Mod and why its not possible to eavesdrop computer traffic despite a man-in-the-middle, eg: if you are using HTTP/S in the browser.