Regarding the famous shot (spoilers)

Because 1. Hithcock was a perfectionist, and had thought it out in advance in story boards. 2. There wasn't a location that fitted his vision, and 3. It wouldn't have been able to film it the way he wanted it even if there would've been such a location.

Also, Hitchcock had been quite lazy and worked in studios for his entire career, and was at the end of his career. And he was simply used to doing films the way he did them. He had a plan for how a scene was supposed to be filmed, ordered sets to be built to that specification, and then filmed them that exact way. His films very seldom differed from story boards to finished results, they were almot always filmed exactly the way he had thought it out from the beginning.

That means, every interior shot is done in a studio, every exterior shot was done on location. And that means there has to be a transitional cut between those shots. He was old, he was a little bit lazy, and he was simply used to work that way. And he didn't think the film suffered for it. Knowing all of that, I think it works as seamless as possibly can be, there are only aficionados like us that notices things like that. For 98% of the audience, it doesn't even matter, especially so for the viewing public at the time.

I thought the shot was masterfully done. Not everything has to be CGI to be impressive. Was always a fan of more practical effects. I loved the camera cuts in Rope as well.

That is observant about Hitchcock and how he worked.

But, in the moment, I very much bought "the shot." Even though, if I had thought about it, I would think about that being a set, it was very well done! And, my immediate reaction was that they cut because they were going from interior (tungsten light film) to outside (daylight film).

I know that a great many people on here know this! But, in case you don't: While today's digital cameras have their sensors set for whatever color temperature, film uses daylight film (more blue) and tungsten film (more red). The lighting used matches the associated color temperature.

So, in that moment, I felt the cut was to change film. You can see how the interior had gone reddish, which is what would happen if you were shooting with daylight film, and seeing part of an interior lit as it would be.

All I could think was: What kind of camera set up could they have used?

But, after what you all have said, I can see how it was actually done! To me, it was a very well-done illusion, and cinematically, it worked beautifully!

I. Drink. Your. Milkshake! [slurp!] I DRINK IT UP! - Daniel Plainview - There Will Be Blood