attached is a patch file that works on my site, simply replace ow_static/plugins/base/js/ow.js with the attached code.
as always back-up the file before you do anything.
url = $(this).attr("src"); wmode = "wmode=transparent"; if ( url.indexOf("?") != -1) { $o.attr("src", url + "&" + wmode); } else { $o.attr("src", url + "?" + wmode); }