This is a leagal issue. I don't know the details, but browsers aren't allowed to play automatic interactive contents anymore. Some company got a patent on that.
So Microsoft had to make a change and requieres now an user interaction, bevor playing the content. This doesn't infringe the patent anymore.
Opera did the same thing with the newsest Version. Don't know about FF, but if they don't wanna get into trouble they should do the same thing.
To bad, that we have to suffer because of some stupid patents by some stupid company.
