Just a few additional thoughts from an investigator’s perspective:
-make sure the VMS is very easy to use because many interviews are conducted by officers who sporadically use the system and need help burning discs.
-in high-volume detective bureaus such as those at the county jail, it becomes burdensome for a detective to continually stop what they are doing to burn discs for visiting detectives.
-as stated before, make sure audio and video sync properly
-certain portions of interrogations MUST be redacted for court, so an option for AVI is very helpful, but cannot be the primary recording method
-key-based on/off switches outside interview rooms are common, and ensure that you have started recording and nobody can shut the system off if the key is in your pocket.
-detectives frequently don’t back up important interviews and secondary storage media is frequently lost as it makes its way through the system, so more storage is better.