I have seen this close up when I was a Loco driver before I retired , the actual lathe work was quickly done but aligning the wheels to the machine takes at least twice as long . I am a bit surprised that no coolant was used on the cutting bars which do the hard work on each wheel . We also had a weighbridge which used the deflection of the rail when a engine or carriage was positioned in the position between 2 support pads . Also a wheel analyser was used on main line tracks which not only checked for flat spots on wheels as seen in this video but also had heat detectors & audio devices which listened for faulty bearings . The heat detector had problems when a steam engine passed over it & gave false readings to a computer which then gave an alarm indicating bad bearings requiring the train to stop & engine crew examine the wheel concerned .

Cheers Tom in Oz .