From a quick look,
Your problem seems to be not enough power and/or being unbalanced.
Your throttle is pegged to the max but the copter is reluctantly climbing with motors 3 and 4 being pulsed to minimum for most of the flight.
Were you fighting a breeze?
As @bendead noted your battery is barely keeping up with such a large voltage drop and you haven't set up current measuring so I can't tell you any more there.
For further help you really need to give us more detail about your setup and the flight in question.