It occasionally cuts to measuring items with calipers, a multimeter, using a compass, and parts show up on screen with score marks, so I assume the creator is definitely measuring things off camera.

The video is an hour long, but the fast scene cuts, and focusing on the actual assembly actions makes the video somehow more compelling and "can't-look-away".

An engineer is not a YouTube video which is essentially a (maybe) narrated highlight reel of a process. I don’t find it disingenuous to condense this down for general consumption because there just is not a ton of value from showing every measurement, each individual cut, and inevitable mess-ups of this process.