I've come across a really great documentary series from 1992 about the history of computing. I hadn't seen this before I wrote my book, but I wish I had! It almost perfectly follows the structure of my book - at least up to the mid 1990s.
The Machine That Changed the World was a five episode documentary about the history of computing, produced by WGBH Boston and the BBC. It aired in 1992 and was released on VHS but is long out of print and the only remaining copies are old tapes floating around school libraries or in the homes of fans who copied the original shows as they aired.
The show is remarkably accurate and corrects most of the myths surrounding the history and development of the computer. One of the series sponsors was the Association for Computing Machinery, who I guess ensured correctness. So far the only error I've spotted is claiming ENIAC as the first electronic programmable computer in 1946. As we all know, Colossus was actually the first computer and was working in 1943. Colossus however, was top secret and it has only been recently that the history has been corrected.
There's lots of footage I've never seen before and many interviews with the people involved. I highly recommend this. I've indexed this excellent series on The Universal Machine's YouTube channel (it's filed under "Computer History"). You can watch the first episode here.