By dynamic, do you mean that you want to be able to load any image in a certain directory without it’s file name being pre-coded anywhere in your code or to just be able to load an image from within a flash file when a user clicks on a button?
If it’s the second, you can just create a simple flash file with a preloader and your image. That way, when you load the file, the user will see the load pregress.
If it’s the first choice, you might be able to create a flash file with a preloader along with a blank image holder. I haven’t tried this, but you could probably set the image to a variable name and pass the name of the image to it through the URL.
I’ll play around with this and see if I can get this to work. It would come in handy to have something like this.