Cees (and Detlef),
Commercial DVDs are often region-encoded. This "feature" was added to DVDs at the insistence of the movie studios, who wanted to control when movies were available in various geographies. (We [the original DVD Technical Working Group, of which I was a member] had to agree to region encoding in players in order for the studios to agree to publish movies on DVD.)
I sincerely doubt that the DVDs produced by Dick and Ray would have any region codes on them.
-David Pease
'66 French 230SL
P.S. Region encoding is really just one character on the disk that identifieds the region (there are 6 of them) that the disk is allowed to play in. There is no real difference in encoding.
P.P.S. There is also the issue of PAL versus NTSC - perhaps that is what you were thinking of?