MPEG is the codec used to encode the video so that it will fit onto a DVD. It compresses raw video, which is then decoded by your DVD player or your software.
NTSC is a video standard which is used in north america, PAL is used in Europe. NTSC basically means that the video is played at 29.97 frames per second at 50Hz, which differs from PAL. On a PC this does not matter, but if you try to play an NTSC DVD on a PAL TV or vice versa you may have problems. I'm no expert on the subject though.