thats cause it's compressed that way!
reduced the file size from 10mb to 5mb.... 
Argh....!
Knew it.
You're using PCM-Sound aren't you? That's *UNCOMPRESSED*. That's also the reason why you can squeze the files with a compression method.
Start compressing audio too (I can tell you how it's done in VR-Dub, but not Premier)
Recommended audio formats: mp3 or ogg (vobris).
For the later you're gona need VR-Dub Mod.
On a sidenote: with an mkv file (Matroska) you can have subtitles with custom font, size, position - embedded into the container file (mkv) but not burned into the video.
About the new portion - there's too much white glare. (Maybe have suns with no glare?).
The pacing is very good though, and there's a good sense of momentum carried from scene to scene, that lets the action flow even without cluttering the scene with ships and beams and BOOMs - which is good.
A BoE scene could be good, but wihtout buildup, pacing and coreography - highpoints of the trailer so far - it would be just a huge clutter on screen....and you may reserve that moment for the Star Wars project as a tip of the hat.
The Lucifer would work a lot better with a lower ambient factor or just against a dark background, it's the prime 'black-ship' with a scrary red (or now in cutscene colors, red-green) glowmap.
You should go beyond the cutscene effect - I wonder if any ship has acceptable cockpit rendering by now. With that you could give the exact same 'in-my-pants' moment Lt. Ash had....then let the Lucy swoop by, start tracking and show the action from an 'above the shoulder' perspective as it unleashes hell.
I wonder if it would be possible to do orbital bombardment by now (many campaings used the reverse - ground based canons), though you could just show some of Omni's planet models with the Lucy howevering like Damocles' Sword.
PS.: I like the Pirates of the Caribbean soundtrack. Hans Zimmer RULZ in any music though.
PS.PS.: You may have had trouble with the mp3 encoding as Windows likes to *upgrade* the codec along with Windows Media Player.
This or
this should solve that.
The first is an old pirate response to 'Mircosoft's kindness'.
The later is the best damn free mp3 codec out there. It's an ACM codec so Premier should be able to use it.