I believe he's talking about the "window regulator" which is a fancy (and official) term for the assembly that raises and lowers the window.
The window regulator I am familiar with is a scissors lift that raises the window. The failure mode I am familiar with is a weld breaking in the mechanical assembly, so the window isn't lift from each end.
So the failure options are:
• mechanical – broken or worn bearings and other parts
• motor – failure to turn at all or slop and grinding noises
• control system – motor is not energized