One other thing to mention is that for some people, video has very limited value, unless the delivery is particularly inspirational. Reading is a lot more efficient, portable, linkable, etc.
There are reasons to want to hear someone on video: to see how the behave in real-time provides different information about their personality and their mode of thinking. In some cases it may be the next best thing to meeting them in person.
I must say, speeding it up by 40% makes most of these Bloggingheads discussions a lot better -- more interesting and no harder to understand. (Does anybody know why they chose sqrt(2) as the speed-up factor?)
Link.
"Razib Khan has an academic background in the biological sciences, and has worked for many years in software. He is an Unz Foundation Junior Fellow. He lives in the western United States."
Razib's writings can be found on his blog, Gene Expression.