This article is from the DVD Formats FAQ, by jtfrog@usa.net (Jim Taylor) with numerous contributions by others.
Even though DVD's dual-layer technology (see 3.3) allows over four hours of
continuous playback from a single side, some movies are split over two
sides of a disc, requiring that the disc be flipped partway through. Most
"flipper" discs exist because of producers who are too lazy to optimize the
compression or make a dual-layer disc. Better picture quality is a cheap
excuse for increasing the data rate; in many cases the video will look
better if carefully encoded at a lower bit rate. Lack of dual-layer
production capability is also a lame excuse; in 1997 very few DVD plants
could make dual-layer discs, but this is no longer the case. No players can
automatically switch sides, but it's not needed since most movies less than
4 hours long can easily fit on one dual-layer (RSDL) side.
There is a list of "flipper" discs in the Film Vault at DVD Review. Note: A
flipper is not the same as a disc with a widescreen version on one side and
a pan & scan version or supplements on the other. Please send additions to
info@dvdreview.com. (The list has gotten too long to keep in this FAQ.)
 
Continue to: