If you download the file below called "gridview" and TURN OFF MASKING in the display quality menu then you'll see something like this:

Now play around with the Manipulate Bones and bone strengths and the grid will give you a nice visual feedback of how AS handles image textures and the way bone strength changes the matrix of the image.
As a beginner I found that it help me to understand the how bones affect image textures.
Here are the files, don't forget the texture file:
http://idisk.mac.com/muuvist/Public/gridview
Cheers