VCD, SVCD and DVD complaint movies have specific video width and height. If the width and height of your original video is smaller than the ones used by VCD, SVCD or DVD then the overall file size may increase.
The size may also increase if the frame rate of your original video is less than what is required by standard VCD, SVCD and DVD movies.
Video Edit Magic automatically adjusts both the dimension and frame rate to match the MPEG standards.
For example if you put a 240 x 120 pixels, 15 frames/second file to the timeline and make a movie in VCD NTSC format then the created file will be 352 x 240 pixels and 29.97 frames/second. The file size here will therefore increase.
The original file's dimension and frame rate is displayed in the Video Information column of Media Files list under the Collections window.