is there anyone familiar with this program or any dvd burning software that can help me with a problem?

Problem:
when i add a 650 MB movie onto my burning list it is then regestered as 2+GB. why is this? the quality has been turned down to extended play yet its still very high and not the size of the file. ive been trying to make a dvd with these movies that ive downloaded for awhile now and im about to give up.