Ok my friend spent an hour translating the trailer and how cool was it to sit there and watch her do this? Very cool. She's not sure of a couple of things especially with Vincent because apparently he was speaking like the equivalent of Shakespere. But here's what she got and all (even if you don't know her) should bow down to her for doing this.

Tifa: He's not here anymore. (talking to the ringing phone)

Boy: Cloud, where are you?

Hooded man: We have started an investigation that Sephiroth
has left us. What do you think happened?

Girl: Is (.name.Cloud?) sick like Denzel (?) is?

Tifa: He wants to fight alone.

Girl: He wants to fight?

Tifa: No he does not want to fight.

Hooded Man: Kadaj is young and violent. He is very
dangerous.

Cloud: Kadaj...?

Hooded Man: There's only you. We're counting on you, ex-soldier
Cloud.

Loz: Where's your mother?

Yazoo: Have you hidden her?

Kadaj: I need your help, Mother. You're indispensable for
the Reunion.

Girl: Cloud!

Tifa: Run!

Vincent: (Disease name) is caused by the overworking of the system
that works to cleanse your body and flush out foreign bodies.
There's a life stream in our bodies that fights against these
foreign bodies that enter into it.

Kadaj: This Star is working against everyone. It's trying
to stop our growth. That is why your bodies rot away and you
are disheartened. I have a solution to this. Then let's go to
the place where Mother is. Then we could work together like a
family and take revenge on this Star!

Cloud: I can't save anyone. No one.

Zack: What are you going to do when you get to Miidgar?
Let's be friends.

Tifa: Did we lose to memories?

Kadaj: I knew you would come!

Cloud: I came to take the children back
.
Kadaj: This is our big brother, children. It's too bad,
that he's a traitor.

Aeris: You came. You came even though you are about to
break.

Vincent: The heavens deliver the evil that is Jenova. It is
possible to resurrect Sephiroth.

Barett: (Some name) is safe right?

Fighting Girl: Who do you think is using my (weapon)?

Guy on the ground: This is too much fun. Huh? No yet!

Kadaj: Mother!

Tifa: Two years ago, at the final battle, he felt something.
It's only been two years but he lost that feeling. I think
he's found that feeling again.

Kadaj: Aaaaaaaaaaaaah!

Sephiroth: I refuse to become a memory...

Edit: Hooded guy has basically been dubbed Rufus. I just don't have time to go back and change that. Sorry.