This is not an exhaustive list, but should be enough to get you started.
Lee explores GraphQL's core principles, how it works, and what makes it a great tool.
https://www.youtube.com/watch?v=WQLzZf34FJ8
Lee talks about the problems and motivations that led to the creation of GraphQL, and shares lessons learned from the journey.
https://www.youtube.com/watch?v=zVNrqo9XGOs
Dan talks about how the GraphQL execution engine is implemented at Facebook, and dives deep on topics like authorization.
https://www.youtube.com/watch?v=etax3aEe2dA
Eric does a deep dive of the internal workings of executing a GraphQL request.