Looking at the video I saw two things:

 

A blockade runner with some kind of ring round the engine. Looks like one of those Episode 3 hyperspace engines but the runner has a hyperspace engine. So what is it? (can be seen several times in the vid)

*edit*

I looked at it again and this baby also seems to be larger then a normal blockade runner...

 

A massive Ion shot which takes out a Victory StarDestroyer. But it does not like as if it comes from the planet. But perhaps I'm mistaken.

*edit*

Looked at it again and the shots seem to come from a unit behind the space station.

 

Both can best be seen at ~ minute 40.

 

Any ideas?

A stolen Imperial tech that they used to protect the ships engines from attack ? Maybe thats one of those hero ships from EU? A prototype of some sort maybe?

 

For the Ion shot I think one of the ships from Rebels side could be equiped with this or maybe its one of Petros prototype ships true to star wars some how?

might be an advanced Corvette, like in Warlords

yeah, i'd say its a heavy corelian corvette

yeah, i'd say its a heavy corelian corvette

Mind you they have said that you can upgrade units and whatnot, but I thought that those Corvettes did have weird engines.

the Corvettes don't generally have wierd engines but i does look like a hyperspace ring which it cant be so anyone got any ideas what that improvement to the corvette can do?

I think it is the Tantive IV. In another Thread Junker confirms that it is a Hero unit. Therefore I believe that the Corvette is Captain Antilles' Hero Ship.

makes sense but the Tantive IV didnt have those wings but it could be a mod. to set it apart or a upgrade.

um, looks like a correlian haevy corvette to me....

nah its strange its not a heavy corvette because it generally doesn't do anything special to the Ship it just looks cosmetic.

As for the Ion shots, those come directly from Y-Wings. Go frame by frame and you will see what I mean. One shot comes from off-screen in the direction of a group of emerging Y-Wings, and then another shot comes directly from one of them.

hmmmmm.........Very curious. coreillian defenatly. I say updated corvette or Hero

yeah thats what we all think but we know its a Corellian Corvette(Rebel Blockade Runner) we just dont know the specifics of what that ring does.

I like the idea of it being some sort of engine protecting upgrade. If they put Tantive IV in there, it should be true to what it looked like in Episode IV, not with some random thing stuck on it's @$$.

yeah true but if they wanted more protection for the engines why not just make the casing out of a denser metal?

well i think it resembles a coreillian heavy corvete and the ring is used for exter sublight trust for heavy cargo

i think that looking at the picture i looks as if they are engines.