Hi,
Rowvid.com analysis (7.95s-8.55s) shows that robot did pass 6 floor tiles with edge length 31cm. The speed in that time frame was therefore 1.86/0.6=3.1m/s or 11.16km/h.
This is far less than the 9.89m/s seen in motor test station
When you are using the test jig, the mass that the motor is driving "forward" is less than the mass of the controller and battery because of its position near the pivot point.
In your robot the motor is now accelerating the full mass.
You are trying to get load /speed figures from circular motion and use them in linear motion.
You can use your setup to compare motor characteristics.
Tom.... 
PS If I had realized way back in this thread what you wanted to do, I'd have advised putting the controller and batteries as close to the motor as possible, so the motor sees the full load of the mass, but figures you obtain would be inaccurate due to circular and linear motion.