I shot UAS ("drone") footage for our recent R2OC event. There is a thread on this here:
http://www.chiefdelphi.com/forums/sh...hreadid=130179
Andrew Schreiber and BBay_T1296 raise valid concerns. We all agreed beforehand to not fly over the field during match play, and there were some other safety rules as well.
In addition, I think a truly "aerial" camera will not be stable enough for good registration/tracking of the robots.
So I agree with the notion of either a camera fixed to some element of the arena over the field, or on a cable/pulley system as suggested by Tom Line.
The notion of an electromagnetic "dock" for the UAS is interesting; I am not sure I would want something with GPS antennae at its apex, and with motors/electronic compass, etc. encountering a strong electromagnet.