How can I do a non-www to www redirect without breaking Flash security?

Question

So I have a SWF file here (direct link, it autoplays, sorry): http://www.elativemarketing.com/images/portfolio/ann-taylor/anntaylor-video-alia-holiday.swf that, when I have these .htaccess rules enabled:

RewriteCond %{HTTP_HOST} !^www\.
RewriteRule ^ http://www.%{HTTP_HOST}%{REQUEST_URI} [L,R=301]

Fails out with this error:

Error: Slideshow data cannot load due to security issue

I've also tried setting up this in my vconf.conf file:

<VirtualHost *:80>
    ServerName elativemarketing.com/
    RedirectPermanent / http://www.elativemarketing.com/
</VirtualHost>

To no avail. It doesn't seem to have any effect; perhaps I'm placing it in the wrong file?

As for the Flash stuff itself, this is a SlideShow Pro player, and it works fine in their Director interface (even with the redirect enabled), but not once I deploy it to the page itself.