hmm, this is an interesting one... i seem to recall seeing this before months ago, but i don't remember what the fix was...
you might try digging through the old mailing list archives... the search is really slow, but you can use google to search it by using a query like this:
"movie not playing site:http://lists.deconcept.com/pipermail/swfobject-deconcept.com/"
(remove the quotes of course)
there's a couple old threads that show up when you do that search, but i didn't see a solution in the few i looked at.
gave up on scanning the archives... ...but found the solution by experimenting a bit further:
it seems the background color of the swfobject creation replaces the background color of this swf.
when giving a different bgcolor, the flash scroll text is visible on that background. and if i leave the argument empty everything works just fine, bgcolor again under swf control :-)