Question

Calculate position from accelerometer and gyroscope

Answer 1

I am afraid that the answer is not one you will want to hear. It is very, very hard to calculate position from a IMU unit. This video from Google is a very good reference for why (go to minute 24 for a detailed explanation). Basically, you need to integrate acceleration twice to get to position. You also need to remove gravity from the acceleration seen by your IMU. If this isn't done perfectly, the errors add up really fast.

The video you referenced used the information that the ball was rolling on the table to inform their model. They could track the orientation of their sensor to know which way the ball was rolling. They used the radius of the ball along with the angular changes from their board to track the ball in x and y. If you picked their ball off the table it wouldn't work at all.

If you need to track something, you should look for some sensor that can give you information on the position of your object (GPS, video analysis). Then you can use a Kalman filter to combine that with the IMU data to get good positional accuracy.

Good luck with your project.