problem with Timesplitters 2

[the_head]

(1)
i made a copy of timesplitters 2 and it turned out to be 4.696Gb.
i don't have a original game that big so i can't boot it up.

there is a trailer for the new tomb raider which takes up about 150mb.
whould i be able to get rid of this trailer and burn the smaller version of the game to dvd-r.

(2)when i check the size of the timesplitters 2 disc it says 4.696Gb
but when i select all the files on the disc and check the size it, it says 1.350Gb

is this a bug on the disc or am i doing some stupid