If you do a video, make sure it's relevant to your content. If all your video is of you talking - then imho it's a fail. As a visitor, the last thing I want to do is have to sit through a video stream which imparts no additional value beyond that which I would have got reading a transcript, and worse, I'm forced to listen at the speed of the speaker, rather than read at my speed.

The other problem with video is that it makes it very difficult to follow the idea that the article author mentions which is release early and then edit/polish later. Some people can present to a camera off-the-cuff and come across polished and succinct. Most can't however and tend to ramble, waffle, make terrible jokes or um and ahh to buy thinking time. Those types of unedited videos are painful to watch.

Which is not to say I disagree with Dan - I agree that video blogging is an untapped opportunity - I feel it's untapped because too many people think they just need to record an unedited 'on-the-fly' conversation or monologue and that constitutes a good video. Until people appreciate that you need to spend more effort on video to get the same quality of blog post as a 'text post', I think video will remain untapped.