@Cy I will check the video later. Blockchain is optional.
@Cy Yes, I think that's a good video and agree. There are also some interesting crypto going on, such as zero-knowledge proofs enabling selective disclosure, such as in this library: ursa.
There is a lot of thought and collaboration going into designing the systems, as can be seen in the notes from Internet Identity Workshop:
(I attended the last one %aQ7gOfU... and presented about SSB at that time).