Generally speaking, after your video files are burned into standard DVD, which means you can play the final disc on your TV DVD player, the content on the disk will be definitely larger than the original video files since DVD is not compressed. So maybe your original files are only 3GB, but the final DVD content will be much larger. Please note what capacity bar shows for the final output size. If it is not in blue, you can not finish the burning with all the files you loaded.
This FAQ is about: Blu-ray Creator, Blu-ray Creator for Mac, DVD Creator, DVD Creator for Mac, Frequently Asked Questions, Total Media Converter Ultimate, Video Converter Ultimate