Almost a full month and not even a polite "Um, we don't know" from the development team. I guess I need to start looking for a 3rd party module to handle our video needs.

Anybody have any recommendations for a good media player that works in IE and Firefox?

I've had the exact same problem.

Looking at the HTML source for the video, when I select a file from the drop down lists, I have:

<embed src='/LinkClick.aspx?link=skeleton.wmv&tabid=63&mid=407&language=fr-FR'

This does not work in Firefox, however setting the media source to a link (albeit on my site) does work..

<embed src='http://mysite.net/LinkClick.aspx?link=skeleton.wmv&tabid=63&mid=407&language=fr-FR'

This may be an issue with the embed tag as the following does work..

<img src='/LinkClick.aspx?link=aspnet.gif&tabid=63&mid=407&language=fr-FR'

Maybe the LinkClick.aspx needs modification..perhaps setting something like the following?
 
Response.ContentType = "type='application/x-mplayer2'";
Although I am suprised this hasn't been spotted yet if it is not a more web server specific problem..