too much interface, not enough content
Tutorials are very useful, even to the pros.
Most of the content in this tutorial wan't very necessary, but you were wise to point out a few key things that people might have trouble with, adn that aren't really convered in the online help - like the proper trace bitmap threshold settings for making a 1 for 1 vector reporduction of a bitmap sprite.
On a personal note - I dislike sprite movies. Make your own art. [harrumphs]
However, I would spend less time on the pretty interface, and more on creating more content, and a nice clean menu to navigate with. A lot of your users would probably like to see some actionscript tips as well.
Embed your screen shots at 1:1 as .png's and use lossless compression to make the screens easy to read, (you'll be surprised at how little bandwidth this burns).
Your users might also like to be able to print out sections from your tutorial.
Part of me wants to grumble that so many kids are using [obviously] stolen copies of Flash, since the software is a little out of your typical teen pocket-money range. However, it's probably a good thing that talented young people are getting their hands on software tools as soon as possible.
Back when I was young, (People still had 8-track players in their houses, and Michael Jackson was still a black man), it was really hard to get your hands on decent technology. On the up side, there was a lot less emphasis on network security, and you could have a lot of fun with a modem and a tone generator...