around 18:30 min, Erik starts to talk about Dave Turner's language SASL. For those interested in the mechanics of compiling SASL into the SKI combinators mentioned by Erik, I have written a tutorial on how to write a functioning SASL compiler (complete from front-end to back-end). Most of it is based on Dave Turner's original notes on SASL.
Available here: The Construction of an SASL Compiler. The SKI-specific material starts with Section 3.3 (page 19).
(This has always been among the courses my students enjoyed the most — by far.)
Enjoy, and thanks for these lectures, Erik!