Undefined jscript error in IE on 0.4.2 with Flowplayer

I am getting an undefined jscript error on a page which has an embedded floplayer script for playing back flash flv files.

The player has a img tag which is clickable to start the movie. Clicking on this link gets the undefined when trying to get the hostname.

In the uncompressed code it breaks on 667:

667: sourceHostName = originalSourceHostName.toLowerCase(),

originalSourceHostName is undefined

Adding a check for hostname got me around the symptoms but is probably not the best means if clicking this item is trackable.
if (!isDefined(sourceElement.hostname))