I just wanted to add another comment about video presentations. I am of a divided mind about them. A video presentation is an attractive way to present new material but I don't find them useful as reference material. E.g., if there is a phrase or paragraph in a tutorial somewhere, it's easy to quickly click back and scan to that paragraph. A video presentation doesn't lend itself to that very well.
(A minor point is that I tend to scan what's new on the site while at work. Watching a video is less acceptable then reading something during a coffee break.)
Also, written content is more appropriate for substantial material that may need rereading over time. Watching videos more than once just doesn't work well for me.
We had this debate in the early 80's with technical IT training at one place I worked. Our boss maintained that visual and audio presentations transferred more bits per second to our brains than reading technical journals. This was true, I thought, but a lot of those extra bits have to be discarded to get to the meat.
People seem to like them though, as MR reports above, so it's hard to argue with that. It would be an interesting statistic to keep to see how often they are repeatedly referred to in the future, compared with written content.
When I read, I choose what's important; when I watch, the presenter does the choosing. For some things, it works, for other things, it doesn't. There are probably pedagological experts who can better explain why. I can't.
(Of course, it's just me, but I have only watched one of the recent Photokina blogs and stopped it partway through.)