text: why do file sizes increase when i try and burn it to dvd? if im trying to burn a 700mb .avi file to dvd, why does it not fit on a 4.7 gig dvd-r? it has to do with the files needing to be encoded to enable them to be played on dvd players. also, if you include things like personalized menus, chapter breaks, music and other extras to the dvd it will increase the file size further due to all the additional info needing to be put on the disc.