I've just installed the kaltura module on Drupal 6.22 - got all the green lights on the Kaltura settings page after installing. (Drupal to Kaltura Session test, Kaltura to Drupal Notification Status, Cron-Job Status, crossdomain.xml Status). So everything seems good until I want to create a Kaltura Media node, it then gives me the modal window with a page not found in it.

Update -------> My bad, I had some custom rewrite rules in my .htaccess file which inadvertently broke the kaltura upload window. All fixed now, I just need to try and recreate my .htaccess rules in a way that keeps Kaltura happy.