Covers some specific hardcore subjects, notably quantum electrodynamics, in full mathematical detail.
Could be more example oriented: "this is what the results is useful for", but amazing on what he focuses on: the mathematical derivations.
Generally involves short talks + a detailed read-through of a pre-prepared PDF. He has refused giving the PDF or Tex source as of 2020 unfortunately.
"Quantum Field Theory Lecture Series" playlist: https://www.youtube.com/playlist?list=PLSpklniGdSfSsk7BSZjONcfhRGKNa2uou