Kaltura CE v3, AWS EC2 image, and Wordpress x7host Videox7 plugin -- cannot play embedded video

Just some quick info: I'm running Kaltura CE v3 through the public AMI image "KalturaCE-3.0.0_64bit_ubuntu-10.4_20110512 (ami-9cad53f5)" available in EC2. I am attempting to integrate it with Wordpress with an external plugin called Videox7, which is a modification of the normal Kaltura Wordpress plugin "All In One Video Pack" for use with privately deployed Kaltura CE instances. The Kaltura CE server and Wordpress server sit in completely different datacenters and networks.

I can't play embedded video generated from Kaltura CE using Wordpress. When I generate an embed code from Kaltura's management console the video plays.

The URL that the wordpress plugin gets to the KDP player is:

http://REMOVED/index.php/kwidget/wid/_101/uiconf_id/535/entry_id/0_i6mv0wur

and that pulls up KDP v3.3.9.2. No videos play from this KDP, only transitions, although the time scrub bar indicates that is trying to play something. If I open the URL straight in the browser it has the same problem.

If on the other hand I generate an embed code from KMC, I get this URL to the KDP player:

http://REMOVED/index.php/kwidget/cache_st/1319836677/wid/_101/uiconf_id/1727873/entry_id/0_i6mv0wur

This pulls up KDP v3.4.10.1, and the video plays in full either embedded or if I jam the URL straight in the browser.

I've noticed there's actually four KDPs installed in /opt/kaltura/web/flash/kdp3. I would like to configure it such that it uses the latest (v3.4.10.1) which appears to play the video properly. Does anyone happen to know what is wrong and how to fix it?