Thanks:
Your answer helps me answer my real question which was what is the difference between a security DVR and a multi media DVR.
From within your replays I think I see the difference. The security DVR records in low frames per second while the multi media DVR records in real time. So I can use a security DVR to monitor the environmental experiments because "watch metal rust" is a long slow process. However recording a student speaking requires real time video recording and must be at 30 fps.
Would you agree with the above?