Peter Lewin on Expectations and Uncertainty

Peter Lewin (Professor of economics at the University of Texas at Dallas) talks here about expectations and uncertainty. Lewin claims an affiliation with the Austrian School, and in particular Ludwig M. Lachmann.

It seems to me that he misses a fundamental point about radical uncertainty here: this type of uncertainty concerns the inability of agents to calculate risk in the sense of assigning objective probability scores to outcomes in the future.