[ssamadhi97]

the method described in the thread crazyman linked to is based exclusively on patching headers in the dvd data to trick the dvd player into playing it back at a different frame rate. (this trick should even be perfectly reversible, as far as I can tell)

Apparently it doesn't work with many dvd players though.

And tbh I can't imagine how this can really work because the speed of the audio track will not match the speed of the video any more afterwards since it has a fixed sample rate which will remain unaffected by this modification.