Many or most developers I've spoken to have little or no familiarity with ActionScript.
I've spent two years working primarily in ActionScript 3. So if you have any questions about the language, about Flex, about Flash Player/AIR, about best practices, and so forth, I'll try to answer them.
Getting started with Flash development is difficult for CS-trained programmers. Most tutorials seem aimed at designers or animators. I haven't seen a good description of the end-to-end tool suite for flash or a list of best practices (e.g., using Flash for animated assets, exporting to a SWC and importing symbols as objects).