Going to http://teamtreehouse.com/ in IE 9.0.8112 the video on the right comes up and shows the still image. You click the image, and it plays fine.
I have Firefox 18.0.1 as my primary browser. When I go to that site, the still picture does not show, nor will the video play if you click on it. If I go to that page, and look at firebug, I see some "403 Forbidden" errors.
I thought this might be an mp4 issue, but I was able to watch mp4 video on another site. (QuickTime in browser plugin)
Looking for any suggestions to get this working in Firefox or how to troubleshoot this further.
Update: In the error console I see a lot of "Warning: Unknown property '-moz-border-radius'. Declaration dropped." warnings and I see errors similar to "Error: [Exception... "'Image HTTP->HTTPS redirection to https://a248.e.akamai.net/...3cf7.png' " but nothing relating to video.