How can you remove poster image or down-level Stage?

I setup a still image as a fallback, but even though it's a .png file, the animation shows up with a white background.  At least I think that's waht the problem is.  Here's the link to the test website:  http://jjds.plumthumb.net/site

Another unrelated problem, the animation only shows up in IE and Safari (not Chrome or Firefox), so you can only see the animation in those two browers right now.

Thanks for your help.

Cheers,
Jeff