I'm also still having a hard time figuring out how the EC managed to take up more memory than LotSB.
Apparently, pre-rendered cutscenes take up a lot of room. I've seen it suggested that the slides used in the epilogue were supposed to be proper footage, but they couldn't fit them within Xbox Live's 2GB DLC limit, so they used artwork instead. No idea if that's true or not, but it sounds believable.
You know, from an artistic POV I think I like the idea of the slides better than pre-rendered cutscenes. It gives the epilogue an almost storybook quaity, which is quite appropriate given the post credits scene.
I could have done with some more pre-rendered scenes during the Londo missions. It would have been a good place to show the Rachi, Elcor, Geth etc...actually, for some reason I don't think *any* Geth showed up in my ending at all. Not even in the "fleets reporting in" scene. While vexing, the absence of a reminder that they were there at all did make the destroy decision a little easier.
Speaking of the post credits scene; anyone notice that the new pair you get in that scene after the "refusal" ending aren't Yahg? So much for them running the next cycle.