Very useful post; thanks. Of course, automatically playing or moving content is also annoying to many of us with no disability whatsoever. Just as I won't link to a .pdf file without including "[PDF]" as part of the link, I won't link to any site with auto-playing media without including a similar bracketed warning about what's coming. The only exception I've made is sites with javascript sliders, but now I'm thinking that's an oversight. (I wish we could convince WordPress developers that the slider craze needs to go away, for the love of all that's holy. Is there any evidence whatsoever that seeing lots of moving things on a page draws people in, rather than scaring them off?)