He has a point by not using gap shims at the thrust bearing but I doubt it is that good noticable. Used shims are always deformed and can give that spring effect.
One important thing he did not show is when you push on the collar you have to pull out the crankshaft.
That tool is expensive and made by Xceed (Serpent), if you know someone with a lathe ye could make an adapter like that and for less than 20 dollar you can find a digital dial.
Also the shims is wise to look arround on ebay/alibaba, bags with 100pcs of 1 thickness can be found for a few dollar. Get them in several sizes and you do not have to re-use them.
Regarding the endplay, too much endplay is killing the thrust bearing. When the clutch is engaging the ring with the balls needs to re-locate the grooves of the rings with the possibillity to get damaged.
Sadly you do need some endplay due the expansion of the clutchbell because the heat but a zero endplay is possible by adding a spring with the endplay shims. I was searching for a suitable spring and found a small wave spring.
I have found a thin wave spring with a 5mm hole. You need to set the endplay to 0.4~0.5mm and add this small spring. It will push the clutchbell from the shoe and push the thrust bearing to zero play. Some people use a normal 0.1mm shimm and bemnd it a bit hollow to act like a spring.
With this saying, it is also important that the normal bearings can slide freely over the crankshaft so I always oil the crankshaft. You also have to check the end tip of the crankshaft and the beginning of the clutch top piece (holding the thrust bearing). By screwing them tight together a small edge of deformation can show up preventing the bearings to slide over the shaft.