First please add the link to your deviant art home page so we guys could see your works. Now to your question...
What you are trying to do isn't possible in HTML. Flash can't be used as background. But there are alternatives. I'm assuming that your goal is to add animation (with no interactive elements) in the background of your text.
1. Position your html on top of the Flash object
you can position your html above the flash as MackTheKnife suggested. If you want to do that it is important that you define the param "wMode" of the flash object as transparent. The code for this will look like this
param name="wmode" value="transparent"
If you don't define this param then the Flash object will always apear on top of other html elements on the page.
This approach will not work in all browsers.
2. create a gif animation from your flash movie and use it as background using css
This solution will work in all browsers. the code will look like this:
<div style="width:[your width]px;height:[your height]px; background-image: url([your image]);">
Your content will go here
</div>
You could also control the position of the background in the div and prevent it from repeating.
