YAY - I found a solution from a tutorial! 1) Enter "about:config" into the URL bar.
2) If you get a warning message about "This might void your warranty!" continue on.
3) Now, type "autoplay" into the search box.4) This will bring up a preference named "media.autoplay.enabled." Double-click it so that the preference changes to False.
And from what I see at my website it works!
