Yep.

I can understand that some people express themselves better by speaking rather than writing (I'm just the opposite), but if you want to get your message across, you really should consider what format delivers the best punch.

Audiovisual presentation is obviously great if you've got a lot of visual information. Video clips, photos, sounds, or abstract information that needs visualization (e.g. graphs).

However, if your main content is basically prose (explaining or discussing ideas), you can't beat written text. You can quickly skim over it to get an idea if it's interesting at all, it's quick and easy to return to a particularly interesting spot, it's easy put in references and links, it consumes little space and bandwidth, and you can read it anywhere without disturbing anyone. Most important of all, you can search the text.

What I find bizarre is how the videos with maybe 2-5 minutes of essential content are padded with 5-10 minutes of flashy intro graphics, soundtrack, scrolling text, and visual and sound effects that add NOTHING to the content. They serve merely as eye-candy, a distraction and a source of frustration when you're trying to find a particular spot in the video.

If you opt for a video presentation, please make sure the narration is easy to listen. Most videos I've bothered watching are narrated by a mumbling voice stumbling over the words. You've got to strain to catch the meaning. That, or they use a robotic voice for "anonymity". The horror!

Don't pad the video with useless graphics and sounds. If you've got 2-5 minutes of content, settle for that. There's no rule saying that a video has got to be 20-60 min long to be credible.

Hyperbole makes you sound like an ass. Go for a neutral tone and let the watcher draw the conclusions him/herself.

Wild gestures and moving your body a lot makes you look like a tard, too. You don't have to be stiff like a corpse, but please control your hands and don't lean in and out of the camera. There's a lot of information on the net about the body language of a good stage/video performance.