I’ve been looking into Flash Accessibility for a number of projects and I’ve been cautiously pleased by what I’ve seen. It looks as though the Flash player version 6+ and Flash MX 2004 have incorporated a bunch of new accessibility features that allow them to work better for average users as well as for users with serious disabilities. The Flash player now hooks into the MSAA in Windows to work with screenreaders. Flash is also good for such things as text zooming (and image zooming) and you can actually outdo browser support for accesskey attributes by using keylisteners to provide keyboard shortcuts within your .swf.
It looks as though Flash is headed strongly toward being capable of delivering highly accessible content that will work for users with a range of disabilities.
A few things to keep in mind when building Flash movies:
1) Don’t keep everything moving, especially if users have to interact with it. While swirling navigation may seem cool as a concept it can be a nightmare for users with visual or motor impairments.
2) Make sure that motion and sound are turned on by users rather than turned off. Start video or audio after they hit the play button and make sure it can be turned off. Turn off animations until triggered by a deliberate user action.
3) Clearly mark what links keep users inside the .swf and which ones take them outside of it within your site or to an external site.
4) Always provide a child element in the object tag when placing a .swf in an (X)HTML page that serves as alternate content in case users can’t or don’t have the Flash plug-in.
5) Make sure that you set the tabIndex for everything in the movie and make sure it makes sense.
6) Turn accessibility features on for all elements, except for animated text tat will cause screenreaders to keep going back to the start of the page. Provide names and descriptions that will be useful when read to a user.
7) Use keylisteners to simulate accesskey functionality. You can create shortcuts to navigation and functionality in the .swf. Be sure to tell users what the shortcuts are early in your movie or your effort won’t really help anyone.
8) Make sure that all of the functionality works from the keyboard, if you use inaccessible components like sliders be sure to provide a keyboard interface for users with severe visual or motor impairments who cannot use a mouse.
These are just a few of the ways that you can make your .swf more accessible and usable for all users. If you have further suggestions feel free to add them in the comments.