There are 2 reasons why Amazon say that the DVD may not work outside of the US or Canada.
Stuff from there is recorded in NTSC which is, I'm sorry guys, a low quality version of what we use here in the UK - PAL.
Try watching an old episode of Columbo or Murder She Wrote on a good flatscreen TV, compare it to a UK programme and you will see what I mean. That's why High Definition has been in the US for a few years and only recently in the UK.
If you have a decent enough DVD player and a TV that will display NTSC then you'll be fine.
The other thing is that it will be region 1 encoded and we are region 2 in Europe. Most DVD players can be region modified to play anything, some occasionally need to be 'chipped' others require an engineers remote programmed specially to unlock certain makes of DVD
