While Flash is a great method for delivering content to the web, its method of delivering text isnt always friendly to screen readers. Screen readers read text on a web page out loud for those who do not or can not read it for themselves; they can also identify links, but not when those links are part of buttons in a Flash movie.
However, Flash does have accessibility options that make it easier for screen readers to work with your published movies. You can set accessibility options for an object, button, movie clip, etc. by selecting that item on the stage and then clicking Window->Accessibility (Alt+F2).