The way I did it on mine was to use a cheap laser pointer. I fixed it to the table, in my case by making a little 3D printed plastic holder with magnets, but any clamp will do as long as you can keep the button pressed and the laser lens over the centre of the table.

Shine the laser across the workshop (as long a dimension as you can manage – and measure the distance) onto a piece of white paper on the wall. Mark where the dot hits the paper. Set the backlash compensation to zero. Traverse the table 10-20 degrees one way, and traverse it back the same angle. Measure how far the dot is from the original mark and you can use trigonometry to calculate the backlash angle. For example across a 3 metre workshop 1 degree of backlash would be 52mm – 1mm of backlash would be 1 minute of arc.

An easier way (particularly if the controller wants the backlash in steps) is to repeat the above, then use the jog function on the controller to move the dot exactly back to the mark. The number of jog steps required to get it there will give you the backlash. Test both ways and average.

I’m not sure if that video is measuring backlash as the chuck is moving in the same direction each time it returns to zero.

You need to run it in one direction to zero and then start jogging back the other way. if the needle moves as soon as you start to jog then there is no backlash but if it takes a couple or more clicks record how many jogs and how far each jog is and that will give your backlash. Do it in a few different positions an davarage out the results.

Think of it like moving a manual mill table with a dti against your work you wind the handle until dti reads zero and then start winding the other way, very unlikely it will move as soon as you turn the handle due to backlash which can be read off the handwheel. You are just reading the jogs which will include any backlash in the drive as well as the tables backlash