"Let's create an implementation for these two setters and getters."

He is just moving from the header file .h to the implementation file .m. It looks strange the way it switches between the two files but I believe he is just copying and pasting the declarations and replacing the semicolons with the curly braces. Hope that makes more sense!

I see. That's helpful, thank you.

I thought you had to click on the .m or .h links in the panel to the left to make that switch. Is there a keyboard shortcut that I should use?

Also, it looks like his switch from .h to .m is reflected in the location bar towards the top of the screen, but the switch isn't reflected in the file location panel on the left side of the screen (and if there are other more accurate names for those panels than "file location bar" or whatever, let me know). I see he switches a couple times like that in the video. Is that significant?

Since I navigate between the different files by clicking on the panel on the left, I just want to make sure I'm going to the right place.

I think the shortcut he is using is Shift + command + page up/down but clicking the files on the navigator should do the same. For the names, the one on top of the editor area is called jump bar, and the left panel is called navigator.