I had a .3g2 video file which I put on an apache server and it did not recognize the file as a video file, so I checked the mime.types and httpd.conf file and they did not have that file extension. A quick search of the web showed several different mime type possibilities, and it took me a while to find the correct mime types to add to the server. I found some RFC documents which spelled everything out. I added the following lines to my httpd.conf file. Note that the mime type "audio/3gpp" is appropriate for audio only, and not video, while the "video/3gpp" mime type is appropriate for audio and/or video.
AddType video/3gpp .3gpp .3gp
AddType video/3gpp2 .3gpp2 .3g2
MIME Type Registrations for 3GPP2 Multimedia Files
MIME Type Registrations for 3rd Generation Partnership Project (3GPP) Multimedia files
Mac OS X and Linux things