Apologies if this seems a daft question but here goes. I understand that a double sided double layered DVD has a 19Gb capacity. So why do the manufacturers(film studios) insist on putting out films on multiple discs? I was given the Twin Towers 4 Disc edition for Christmas. I love the film but I'm amazed that a caption comes up and tells me that part 2 of the film continues on disc 2. Why did they not make use of the flip side of disc 1 instead of going to the expense of creating another disc. DVDs are supposed to be double sided but I only have a few of these beasts (Friends, A Bugs Life) yet the manufacturers seem obsessed with multiple discs. These box sets of unecessary extra discs are the same width as VHS tapes taking up retailers ( and my) shelf space. What was the point of the two original opposing formats (Double sided & double layered) combining to form the DVD we know today if one of those formats is totally ignored?