“Did you know that they're making a new Ghostbusters sequel with the original cast?”

You're talking with a group of friends about movies that you like and someone mentions the 1980's comedy Ghostbusters. You recently read some news that a new Ghostbusters movie is being planned, and that it will star the same actors from the original movie. You say:

Did you know that they're making a new Ghostbusters sequel with the original cast?

Did you know that (clause)

You use this when you have an interesting fact that you don't think the listeners know, and you want to share it with them.

they're (doing something)

In casual speech, you can use "they're ___ing" when you don't know or don't care who's doing the action. Another example:

Look at that (pointing to a sign) - they raised the price of gas again!

In formal situations, when you want to express what an unknown person or group has done, use this structure:

Did you know that a new Ghostbusters movie is being made with the original cast?

a sequel

A "sequel" is a movie or book that continues a previous one. The sequel usually uses the same characters as the original. The sequel will often be given a number, like "Shrek 2" or "The Godfather, Part 2"

the original (something)

The "original" of something is the first version of something. For example, the original members of a band are the people who were in the band when it started. The "original flavor" of a food product is the first flavor that was made. And so on.

the cast (of a movie)

The cast of a movie, TV show, or a play are the actors. The difference between "actors" and "cast" is that there are many actors in a movie, but only one cast. "Cast" refers to the entire group together.