That's called a digital copy and when its applicable (not on the HAMLET 2 release, unfortunately) it comes on a separate disc. A 'code' doesn't make your DVD download the film onto your computer -- the digital copy disc does. The code is only so that you don't share the film to others, etc.
Now... you don't need a digital copy of the film to download it onto your computer which will allow you to put it on any portable media device: iPhone, video iPod, iPod Touch, etc. There are numerous free programs that'll let you do this from the actual DVD.