Not to be critical but some info was left out and it is very important if you are doing true segmenting other than simple pens. I did not watch the whole tape but that should have been mentioned right off the start. Just my opinion.
If you are doing segmenting work other than simple pens accuracy is so key. To begin with the blade needs to be parallel to those miter slots. The back fence stop needs to be 90 degrees to the blade. The tracks must be parallel to the back fence and so on.
When ever I build those sleds I will lay the hardwood runners for the miter slots and then line up the sled material with the back side of the saw. That is for appearances which is pretty close to being where I need it. But then after I attached the runners permanently I then raise the blade to cut a slot through the sled. I now have a reference point for my back fence which is 90 degrees off that blade cut. Then add whatever tracks or stops you want working now from 2 points of solid references. This sled is now fitted for this saw and unless you do any further adjusting of the blade tracking then it should always be good. All angles and measurements come off the blade and no other part of a saw.