Thank you, Yuki! I set the files to publicly viewable for both sites: qa29.longsight.com and sakai-29.rutgers.edu and both wma and avi files played in FF20.

I reproduced it in FF20 and also in Chrome. I'm feeling it is not a bug of Sakai, but this ticket might have produced one of good know-how to use Sakai.

i.e., Those movie files exist in Resources. It can be playable by setting those files to 'This file is publicly viewable.' in Resources.

I have some information I can add to this.
I installed the plugin for FF:
http://www.interoperabilitybridges.com/windows-media-player-firefox-plugin-download

I then tried to insert an avi file using FF and it looked like it worked, but when I went to play it, you can see the player trying to do something, but nothing displays. This same file plays in IE9.

I saw this happen on both qa29.longsight.com and sakai-29.rutgers.edu. If you look under announcements in https://qa29.longsight.com/portal/site/1507347e-1f06-42ab-a229-08a1018fdebf/ you will see announcements using avi files.

Uploading a video from FF20.

I checked this again and agree with Teresa - updated title and description.

I had no problems adding both wma & avi files in Syllabus on https://sakai-29.rutgers.edu. However, neither played in Firefox. Both played in IE-8.