I share your preference for text over video in many cases, although I think Dan Olson makes extremely effective use of his medium in a way many other "video essayists" do not. As far as age goes: before the Internet or even TV, people would go to see lectures and presentations for entertainment. Political speeches and debates were much longer, too. I think there's always been a desire for information delivered verbally in a compelling way. We just have different ways of delivering it now.

I also wouldn't take the transcription of older speeches too literally.