Can't watch the video right now, but the slides (available at [0]) list these four "forgotten ideas":
1. Linda Tuple Spaces [1]
2. Flow based programming [2]
3. Xanadu [3]
4. Unix pipes [4]
[0] https://codesync.global/uploads/media/default/0001/01/de7dfa...
[1] https://en.wikipedia.org/wiki/Tuple_space
[2] https://en.wikipedia.org/wiki/Flow-based_programming