you can make ISO image of your DVD with Paragon CD-ROM Emulator. Then you'll be able to edit the image. homepage - http://www.cdrom-emulator.com
Use DVDDecrypter to rip and demux the DVD into separate audio and video files. You probably end up with AC3 audio file assuming that the audio track was recorded in Dolby Digital format. Then just go to doom9 and find tools to downmix the AC3 audio to regular stereo WAV and you're done.