Quantum Cryptography Explained

A lot of minute things I think you oversimplified too much in this video... Or in the first case made needlessly complex: 

When you told us how you could use prime numbers to encrypt your message (you chose 11 and 13 as prime numbers, and multiplied everything with 11*13 = 143) you aren't actually showing the need for an asymmetric key. In fact you could have used any number, say 144 which is a composite of a lot of 2s and 3s, and the code would work the exact same way. As long as the sender and receiver agrees on the key the encryption works.

The only reason to use one way functions is the much more complex asymmetric algorithms as RSA which i agree very much you shouldn't go into detail on in this kind of video. But for those who are interested basically the product of the primes is PUBLICLY known so anyone can use it to encrypt, but the algorithm is made such that to de-crypt you need to know the prime factors (which you keep private). 

The other one is you say that a random number can be used to encrypt a message if it is truly random. This is correct only if the number is as large as the message! There's a big difference between a random number and a random number at least sooo big.