That 1975 APL demonstration is lovely. Much has been preserved in Dyalog and GNU APL - it's very interesting to see how timeless the core APL functions are.
I'm very fond of a number of videos by the late John Scholes narrating APL solutions step by step, including the well-known demonstration of Conway's Game of Life in APL (0). His videos on depth-first search (1) and solving sudoku (2) are also brilliant.