Q3SDC2 was a Quake 3 engine modification allowing server side recording and playback of multi view demos in custom SD3 format. These server side demos were thought to be mod-agnostic, however in practice their compatibility with different mods varies. Most ‘standard’ mods like vanilla Q3, OSP and CPMA used to work fine though.
Technically, Q3SDC2 was a ‘clean’ reimplementation of my early Q3SDC (Quake 3 Server Demo Center) hack, this time based solely on GPL'ed Quake 3 engine source code. This allowed to integrate it nicely into the server subsystem, without using nasty stuff like real-time VM hooks. Q3SDC2 lacks some features Q3SDC had, like the ability to play back client side demos, organize playlists, etc.
This project is no longer in development since 2006. Source code is still available (1.7 M) for historical purpose. It is very unlikely any new releases will be made.