This Guide gives a quick overview of the 'Patch' method, used to make a PAL disc appear as if it was NTSC or an NTSC disk appear as PAL. This method requires no re-encoding, and takes only a few seconds.

NOTE: This method may not be supported by your player.
( Your mileage may vary )
If this method does not work in your player, then it simply means "It does not work in your player". Please don't PM me asking for a fix. I didn't invent this method, and I claim no responsiblity if it does't work
Let's say your granny from a PAL country decides to send you a DVD for Xmas and you live in an NTSC country. You get it and it won't play in your DVD player. Give the link below a shot. It involves copying the contents of the DVd to your HDD, editting some .IFO files, and then burning those contents to a recordable DVD disc.

http://www.videohelp.com/forum/viewtopic.php?t=221928

Give it a go and hopefully it will work on your external DVD player.