Just to be clear (from some of the posts I read it seems that the wrong impression may have been given...)
The Orbiter (in this case the on screen Orbiter) is a "remote control" functionality, but isn't limited just to controlling the local MD it is running on, it can be used to control other MDs as well... ie tell them to start playing media remotely.
The second part of the question was whether you can then monitor what other MDs are playing. It should be noted here that this is not a function of the Orbiter as it is just a remote control. HOWEVER, as a result of it being a very flexible control system, there IS a function that allows you to instruct the local MD to take a copy of the stream going to a remote MD and start playing it locally, by using the remote control functions of the Orbiter. The end result is much the same, but conceptually you can see this is different. This is why it is understandable that it isn't as "elegant" as it could be, like totallymaxed pointed out, because it isn't really an extra (monitoring) function, it is just using the remote control functionality in a specific way to achieve the result you are looking for. This is also why (fibres) why, yes, it will be "full screen" and in fact identical to if you were sitting in front of the other MD - it isn't additional functionality, it is just 2 Orbiters/MDs playing the same file that just happens to be at a (~)synchronised point in that file.
To do the 9 thumbnails view, suggested, would be a possible extension I guess, but is definitely additional functionality, not simply an exension to the described process in this thread, so not a small mod! Plus given that the MDs are playing from file shares using file sharing protocols (typically) then you would need 9x the network bandwidth to achieve this and that could be a major problem depending on the source material bit rates. Putting intelligence at the source end to send only certain frames/recompress/otherwise reduce the bandwidth needed would be an even bigger undertaking for a single feature and rended the feature incompatible with source devices that couldn't run that "agent" software such as NAS's, etc....