A little added info:
We (Apollo) check each spindle for runout before putting them into a machine. Our spec is that every spindle will have a TIR < .001" when measured on the inside of the taper. We have yet to build one with runout above .0005" and the average is about .0002-.0003".
We don't spec runout on the cutter shaft, like the video shows, because we've found that the collets can really contribute to the runout. The first batch of collets we ordered added a lot of runout so we ended up buying the next higher grade for production.
Thanks for the video.