Here's the best approximation we've been able to come up with for the dialogue in the Halo 2 Trailer, with some help from Ferrex.

Later, revisions were provided with the help of Jay Weinland at Bungie, Electric Sheep, shibby, Kyle Burke, Louis Wu and others in the HBO forum (italics):

Pilot: Sir... they just folded inside our formation!

Admiral: Son, I need you to calm down.

Pilot: ... additional contacts ... moving to engage.

Admiral: get your picket back to rally point alpha ...

General: Admiral, you can't let them maintain orbit.

Admiral: I'm trying, General, but we've lost advantage within the lunar perimeter.

Admiral: My frigates are combat ineffective, and the fighters, they don't have enough punch to take out a Covenant assault carrier.

General: Your pilots let up, and down here, it's the goddamned apocalypse.

General: I'm asking you to re-target the orbitals.

Admiral: And let more of them slip the kill zone? That's insanity! There's nothing more I can do!

Pilot: The core defense is too intense, our grid is maxed, I don't think we can last another run.

Cortana: Admiral, tell your men to hold their positions. Reinforcements are on the spoke.

Admiral: The entire fleet is engaged, Cortana. With all respect, what the hell sort of reinforcement have you got?

Tech: It's passing below your position, ma'am, proximity zero.

Cortana: What if you miss?

Master Chief: I won't.