They are using Adobe HTTP Dynamic Streaming technology which is pretty much same as Microsoft Silverlight Smooth Streaming. both technologies use fragmented mp4 files. it's easy to download the fragments but the main problem is to mux those fragments into playable file.
ISMDownloader uses it's own muxer to download fragmented files and mux them as mp4 or mkv. with some modifications same can be done for Adobe streams but this program is not open source. AFAIK currently there is no tool available to mux those fragments into playable file.