http://kb2.adobe.com/cps/402/kb402865.html

On the Windows 2003 server, open the Internet Information Services Manager.

1. Expand the Local Computer Server.
2. Right-click the local computer server and select Properties.
3. Select the MIME Types tab.
4. Click New and enter the following information:
5. Associated Extension box: .F4V
6. MIME Type box: video/mp4
7. Click OK.
8. Restart the World Wide Web Publishing service