Tom,
I tend to trust a person who has done 1000's of carbs. Not a few. Keep in mind he is doing a video and, by his own admission, he is not concentrating like he would if building a carb in normal working conditions. He is thinking of what to say and explain. He does an excellent job WITHOUT a script. Try that sometime.
Let me dispel some of your criticisms.
1. If there is no tag, he is giving us an idea how we may ID the carb. We know it's a B. As you say, parts are mixed and matched. Which proves that the differences are subtle. As you must know, the kit contains unused extra parts. Gaskets, balls, clips.... These parts and the instructions in a kit cover the differences. They cover the mismatched parts that may have been used. If there is no tag and parts are mismatched, his video helps explain what kit parts to use. None of us could identify a mix matched carb. . He tells you which needs 3 balls and which needs 2 balls. He tells you there is a model with a flat pump stem and a round pump stem. Flange hole dimension, the stamped number if available, a picture, the stem and the number of holes in the bottom of the well will tell a person or Mike's Carburetors what kit to get. The tag itself may be mismatched, but we have to start with what info is available. You can buy a kit anywhere you want. Looks like he has 5 kits for B. Delineated by year, make, model. He tells us B is manual choke and BC is automatic choke for further ID. (BV is automatic choke, vacuum operate) The kits come with several base gaskets to cover the variants. He simply had the wrong one laying at his reach.
2. When he removed the power piston he grabbed it at the top. This area has no function and is sometimes smaller. The "sealing" area for vacuum is way down at the bottom. The piston OD is segmented and has a recess in the middle of it's length. If this upper area is scratched/burred it would be "buffed", as he said, and not cause any effect to operation. you would not want to grab it if you didn't have to. If you have to, then you do. The piston does not need a spacecraft seal. If it leaks slightly, it will still pull down. He cautions to be careful not to damage the stem. Don't think there was a bleed hole. Your link seems to cover cars. He would know not to pull on, or damage, stem. I believe he started the video with an unknown condition carb and when he got into it, he kept going. In real life he may have soaked the piston. I think we all would. He did show how to get it out. How to fix a loose throttle shaft link, how to remove stuck plate screws, ran into a stuck ball, broken spring, temporary memory loss, momentary out of sequence assembly...all real life, honest, live rebuild on camera.
3. Just remembering that a marking of RP goes up or down would not orient the plate/disc. The disc can be rotated and installed 180 deg and still see the RP. If you have the RP and take a picture of where it is rotationally, that would work. Or scratch mark it. I have a hunch, after building 1000's, he does this automatically as a fool proof method. All pros develop their fool proof methods and stick to them.
4. He did not use any tools to pry plates into position. He did use a centering tip to find the holes and thus center the choke plate. Choke plates are not critical. When he did the throttle plate he used the same method PLUS he installed the screws LOOSE until he articulated the plate a few time to center it futher, "seated it", held it down and finished the torqueing.
5. I think we can all appreciate someone who sells rebuilt carburetors, for a living, giving us a FREE lesson.
6. This is false and unfair: "With all due respect, the video is a poor example
on how to disassemble & assemble the Rochester 1 BBL." Where is the respect part?
