John, we're a match made in Heaven. We were an early adopter of VoIP about 15 years ago, and M/C was required for overhead and on hook paging. My point after my obligitory jab is the following. Out best practice is to secure all cameras within a fully private LAN with ZERO access from anything but the Video recorders, and a management monitoring probe. For critical systems, and we have a few 24x7 sites where cameras are multicasting to multiple servers. On the LAN side of the video servers where they connect to the corporate VLANs, it is impossible to MC cameras directly to a client in some sort of STREAM hand-off process since the recorders are not Routers.
Perhaps had HomeDepot, Target, CVS, and the federal goverment placed their POS systems on provide non-routable networks a lot of folks personal data had been better protected. Search Google for the following words
casino video system hacks
Is there value in M/C? Sure, and I think its biggest value is multiple recording of the same stream.
I see s lot of security issues with M/C streams from a camera to a client since the protocol provides no authentication from sender to reciever, and we would have a very difficult time defending the decision to use M/C in an audit.
The same security concerns exist if the recorders were to use M/C to VMS clients.
Regardless of the VMS, using M/C requires that you or your client must step up and reconfigure new or existing LAN equipment, and all those dumb switches in departments used as splitters for printer and workstations must go.
Here is good primer for M/C
http://medusa.sdsu.edu/network/CS596/Lectures/ch14_Multicasting.pdf