What's "far-fetched" mean?

What does “stay + adjective” mean?

When you have the word "stay" + and adjective, it typically means to remain. Ex: Please stay alert while driving! I don't want you to get into an accident.

I understand that the word "mainland" refers to the lands that take the largest portion of the territory. Then what do you call the territory that is isolated from the mainland?

I am unsure if there's a specific name for it, but most of the time we just call it by it's given name. For example, in the United States, Alaska and Hawaii are states but are not connected to the mainland. We just say Alaska and Hawaii. The same goes for our territories like Puerto Rico or Guam.

What is "staterooms"?

"Staterooms" are the public rooms in Buckingham Palace, which is located in London, England. These rooms are used by the Queen of England and the royal family receive and entertain their guests for official occasions. Ex: Buckingham Palace has a total of 19 staterooms. Ex: One of the staterooms is called the Throne Room. Ex: Buckingham Palace's staterooms are adorned with beautiful furnishings and art.

What does "after all" mean?

"After all" means ultimately, above all, most importantly, most of all. Ex: She was really a good swimmer, after all. Ex: He likes animals after all.

Why would Jimmy Kimmel say "regular school" in this context?

Jimmy says "regular school" since, in the world of acting, it's quite common for child actors to be taught through homeschooling or with private tutors instead of "regular school" so that they can do their acting jobs as well. And then he also makes it part of a joke by saying that maybe Johnny Depp taught him instead of going to a "regular school." Ex: I was homeschooled for a few years, and then I went to regular school. Ex: You can go to a dance school instead of a regular school if you want to.