How many talking web browsers can read out the content of a flash file?
Well, that is what I was wondering. I steer clear of Flash mostly. I think there can be a case for it, though, when it is illustrating some specific point. I do that once on my site (the only time I use Flash). There is a text explanation of the feature - the flash movie is a video aid so that the viewer can see the product in action.
Provided there is an accompanying text explanation of the feature, I think that is acceptable from an accessibility viewpoint. But I wouldn't use it in other circumstances.
However, Macromedia claim that Flash 8 has accessibility features. But I have not followed this up.