It will try to stay in front of you given the speed and sensor limitations. For example, if you are going too fast it may never be able to outpace you. Alternatively, if you are going slower than 3mph, the sensors are not accurate enough to determine your course so it just stays at whatever angle it currently is at.
http://autoflightlogic.com/beta/autopilotdji/support#854294a6
Are you talking about in Focus Mode when you are manually flying the aircraft? If so, there is nothing preventing you from flying that low, it will just display the warning. If you are wanting lower than 5 meters in computer controlled Modes, you can already select 4m in the settings. Going any lower than 4m with the accuracy of the sensors is dangerous and we cannot allow it.
i was thinking about flying manually but having the camera focus/ move for me... i could not get it work since the camera would always correct up to the sky (was nice and blue

) but my car would have been (will try to post a vid for this) better... we also (cam operator and me) took over control of the camera and that went ok for auonomus flying (follow mode) and him doing the cam...
as for the low alt in autonomus flight i understand you point. i did not know that the sensors are not soooo accurate...
It sounds like you guys are operating with the Advanced Mode controls. If you want the aircraft to move in Basic or Intermediate, just tap Fly to Point A or Fly to Point B.