Hi jay,
the only workaround i found was using the hint caption of the clickfield.
The hint caption is also displayed in html5 when the mouse is over the clickfield. The action of the clickfield should be set to no action.
I use the german version of captivate, so maybe i used the wrong wording. This workaround doesn't work for me, because i need rollover images an not rollover captions, but maybe it works for you.