dvd-r movies on unmoded xbox

[dude]

dudes

i was under the impression that the xbox would not play backed up movies without a mod chip.
just backed a movie up farscape episode 1 to be exact using dvdxcopy 1.3 tried it on a unmodded xbox and it plays perfect none of my other backups work on this machine.
maybe dvdxcopy does some thing to the disc to fool it ?
don't realy know but interesting non the less.