I don't understand why this is even an issue. The gameplay is most important. Look at FF7. It had 3 discs but the last disc barley took up half of the cd space yet it still had all the areas from the other two discs. Doesn't this mean that only the FMVs took up the other half of the cds on the other discs. Only things changing for FF13 are going to be compressed cgi and some music maybe.
If you have both a 360 and PS3 you would obviously get the PS3 version. But if you don't have a PS3 and don't feel like spending 400 to play a game then just get the 360 version. I will get the 360 version as I have no PS3. I doubt the story will make any more sense with uncompressed FMVs







