To enable streaming in MSS format add the /media=mss/ parameter to the link. The link will return an xml manifest to the manifest.mpd file. Various options are available::
The actual segment size will vary, if there are more than ten seconds between keyframes - there may be empty segments.
Example:
http://video.ahcdn.com/key=u-Myh9XWUXP1TMTHaRTnsQ/media=mss5/output.mp4