Minimize differences at the end positions

Mark initial position. Move forward for 25 rotations. Mark end position. Repeat 5-6 times and measure how different the end positions are for each run. Try to minimize the different at the end positions and arrive every time on the same place. What makes the robot move to the left or to the right? Create a video named FLLCasts_MotorCompetition_3 and give us a link below to check it out.