Stephanie,
I think it depends upon how you
are on video on audio.
Some people just don't have the presence for video and audio...I'm not saying you do not but it seems to me that those whose ideas move quickly on video and audio and can speak enthusiastically and succinct can use these venues well.
Some people don't like to be 'on' video but they speak well, so tutorials work well for them.
One of my favorite videographers puts herself in the video and also includes tutorial information to break it up a bit. Her vivacious personality appeals to me. Her name is Jo Barnes and her company is the Social Networking Academy. I believe she is in Australia but every week she gives these wonderful (IMO) videos filled with information I can use. Here's her link to this week's episode.
http://www.thesocialnetworkingacadem...with_Apple.cfm
So I think it depends upon the type of material you offer and in what medium you feel the most comfortable presenting. If you want to do a 'how-to' video then a tutorial would be fine. If you are giving some advice then maybe a video of you would work well. Or you can mix the two for some variety.
Janine