OK, what I've found is that you have to set the permissions of the wp-content folder to 777 to get it to work - which, I am told, is a BAD thing.
at that point, you lose the error about the dat file.
of course, it's not a guarantee that the selector will be substituted... mine just goes missing, no flash appears, but it's a start.
that said, I am going to have to pull this idea out of play, I think... too many iffy things and not enough documentation. I mean, if the permissions need to be 777, just SAY SO. I've looked at 4 pages of posts asking about what is wrong and lots of suggesting that the permissions might be wrong, but no out and out statement from D. Chait what the permissions should BE. or which files need different permissions and what those should be.