I hate video personally. I can’t scan it to understand the overall concepts then delve into the areas I’m most interested in. I also can’t go back later to ‘random access’ a particular area I need to find again – unless I took notes and included a ‘time stamp’ in the process.
From what I know as I study marketing/internet marketing though, shorter is better.
Getting close in, far away & some angle shots mixed together is the current trend and is supposed to hold the interest of the viewer.
My personal recommendation – do both on a website type venue. Some will prefer video and some will prefer text, you can appeal to both types of learners that way.
The beauty of video is the perceived high value and it can be parsed into the other formats very easily – strip the audio, get the content transcribed, and you have it all.
It’s actually pretty easy to obtain now with digital cameras which include video. Viewer expectations appear to be lower too – between The Blair Witch Project, reality TV shows and amateur work appearing all over, you can produce what you need from home with equipment you may already have.