rm mulitmedia filter does not work in Firefox

Since moving the database to new server and upgrading from 1.7.4 to 1.8.4, rm files from my media server or elsewhere bring up prompt to install missing plug-in, subsequently identified as Realplayer 10.5 (which is installed and works inspite of error message in IE7 but not in Mozilla browser).
What has changed between the two versions to break this? There was no error message during upgrade. Installing another daily patch of 1.8.4+ did not help either. No modified code in any of the Moodle source files.

Error message in IE7: error in lines 42, character 11 no such interface supported
Firefox just shows plug-in search page.

The sample link below is accessible through guest login. Video recording plays back in Realplayer in all browsers but in page with error in IE7 and not at all in Mozilla.