To make a webpage accessible to all, it is necessary that users can 'tab' through the different elements of the page. We have recently added a couple of flash videos to our new website. As part of our aim, we wanted to make this flash video accessible. Once the flash element is active, you can use the keyboard to control everything - volume bar, seek bar, turn on/off subtitles, make it full screen etc. We had no problem accessing the video on IE browsers. But we got stuck when using other browsers like Firefox, Safari and Chrome and trying to access the flash video by tabbing on the page.
After 2 days of exhaustive search, we found out that not only the flash videos but no flash elements are accessible on browsers like Mozilla Firefox, Safari, and Chrome. So how does IE managed to fix this problem? IE has got its own ActiveX Control to allow users to tab in and out from a flash element. We have looked at other websites using flash videos (e.g. BBC i-Player, YouTube) in these other browsers and they are not accessible by tabbing either.
The Adobe accessibility team tried to come up with a solution by using flash scripting. When we tried to use that, we found that the fix is okay for Firefox, but it gets stuck inside Safari - which is even worse. Imagine you can only use the keyboard and when you get inside that flash element, you can't get out! Obviously that would be the worst nightmare for the keyboard only user.
As long as browsers don't support tabbing in and out of flash elements, it is not possible to make pages with flash elements accessible to all.