Professor Williams makes a clear case for the way that new technologies in the 1790s and 1950s made jobs in various sectors obsolete. He's right about that and nobody disputes it. Then he comes to the second part of his thesis, that the new technologies which abolished those jobs creates others. Here, unfortunately, his argument fades off into a rhetorical speculation that begs the question:
If there hadn't been the kind of labor-saving technical innovation we've had since the 1950s — in the auto, construction, telephone industries and many others — where in the world would we have gotten workers to produce things that weren't heard of in the '50s, such as desktop computers, cellphones, HDTVs, digital cameras, MRI machines, pharmaceuticals and myriad other goods and services?
His assumption workers laid off in older sectors supply the labor for the production of innovative products needs proof. He doesn't offer any because there isn't any. It takes far fewer worker hour to produce a computer than an automobile and laid off construction workers don't get jobs in MRI factories.
But there is an even bigger loss due to technology than changes on the product assembly line. The new technologies have far greater impact on the labor market outside the manufacturing sector, The computer replaces tellers and accountants because one accountant with a computer does the work of fifty paper and pencil accountants. Those unneeded accountants don't get jobs in computer factories. And banks are small beans compared to on-line retail giants like Amazon which don't have a store and whose warehousing and shipping are heavily automated. The best all those obsolete clerks can hope for is a delivery truck job -- and those are about to be automated as well.
In the earlier stages of our on-going Industrial Revolution, jobs lost in agriculture and blacksmith shops were more than replaced by factory work. In the current information revolution, a similar shift isn't happening because the huge impact of the new technologies is limited to production, it is happening in white collar and even suit jobs as well.