It was a little hard to see in the video... have you done any more testing to see if the unit was built with pre-loaded bearings. How much end float or play in the spindle is there?
Overall what do you think about it? How does it perform? Outer measurements seem a little inconsistent for a spindle though I guess they are not critical. I'm actually surprised to see any needle movement on the runout.
The runoff you were looking at here was ½ a 10th (about 0,0012mm) and that's a very acceptable runoff at this price point! To give you an idea of the prices check this, just renovating a BT40 spindle (re-ginding the surface inside making it run with less than 0,0005mm) will easy run you 3000€. It much more a concern how well surface contact they made on these cheap once. A decent low runoff isn't worth much if the angle is just a tiny bit off (tools doesn't sit right), giving lots of surface roughness and screaming tools (breaks down sharp edges/coating fast)
