What is the meaning of "25th Century Earth as a teacher's voice-over"?

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25th Century Earth as a teacher's voice-over describes the exodus from "Earth that was" and the terraforming and colonization of planets in the new 'verse.

I confused with the words: 25th Century Earth as a teacher's voice-over.

What is the meaning of this confusing sentence?

Answer 1

We need further context:

The pre-title teaser provides backstory for those unfamiliar with the Firefly TV series. The events in the teaser occur prior to the first episode of the TV series: The Universal logo changes to show ships leaving 25th Century Earth as a teacher's voice-over describes the exodus from "Earth that was" and the terraforming and colonization of planets in the new 'verse.'

In this part

The Universal logo changes to show ships leaving 25th Century Earth

the "Universal logo" refers to .

"Changes to" suggests that the the movie transitions from the logo to a shot of Earth. What actually happens is that the word "UNIVERSAL" moves off the screen and the Earth in the logo becomes the shot of Earth used in the movie. Ships are leaving Earth in this shot.

Now we consider the following,

as a teacher's voice-over describes

So, as the above transition happens, from the logo to the shot of Earth, there is a narrator speaking. This narrator turns out to be a teacher on Earth. This is called a voice-over,

voice-over
1 a : the voice of an unseen narrator speaking (as in a motion picture or television commercial)

So as the shot transitions, this unseen narrator (teacher) describes "the exodus from "Earth that was" and terraforming and colonization of planets in the new 'verse". I'm guessing that 'verse is short for universe.

Answer 2

Two things: a) you didn't quote the full sentence; b) about 99.9% of sentences out there aren't really difficult if you know how to read them.

Here is the sentence in full:

The Universal logo changes to show ships leaving 25th Century Earth as a teacher's voice-over describes the exodus from "Earth that was" and the terraforming and colonization of planets in the new 'verse.'

Let's bracket the sentence to make its parts clearer:

[ The Universal logo ] changes to show [ ships ( leaving [ 25th Century Earth ] ) ] as [ a teacher's voice-over ] describes [ [ the exodus from "Earth that was" ] and [ the terraforming and colonization of planets in the new 'verse.' ] ]

Basically, your sentence is:

SOMETHING1 changes to show SOMETHING2 as "a teacher's voice-over" describes SOMETHING3 and SOMETHING4.

Let's take a closer look at the sentence now.

"SOMETHING1 changes."
(That SOMETHING1 is "The Universal logo".)

Changes? For what purpose?
"It changes to show SOMETHING2."
(That SOMETHING2 refers to "ships (that are) leaving 25th Century Earth".)

What happens during the changes?
"It changes while "a teacher's voice-over" describes SOMETHING3 and SOMETHING4."
(A teacher's voice-over = the voice-over of or by a teacher)
(SOMETHING3 = the exodus from "Earth that was"; "Earth that was" is just a name of a planet¹.)
(SOMETHING4 = the terraforming and colonizing of planets in the new 'verse' (a new "universe").)

​　　¹"Earth that was" possibly refers to our earth, but I haven't seen Firefly so I'm not really sure.

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^{Edit note: TRomano's comment urged me to look for the so-called "pre-trailer" on YouTube. (Because I thought this "as" is more like "because" at first even though I could mean "while" as well; I chose to read it as "because" in my first revision, which was wrong. The clip makes it clear that the sentence is just a description of what happens in the trailer (as opposed to why the trailer was made that way).)}

^{Here is the link to the trailer I found on YouTube: https://www.youtube.com/watch?v=WTVdh5UVUXk}