It is the file that contains the video files. Burn with CloneDVD2 or other burner, assuming its been decrypted and sized to fit a DVD5.
I would highly recommend searching this site for scubapetes guide to using dvddecrypter and dvd shrink which are both free programs and work pretty well,his guide will give you a great start.
You may or may not need an empty folder labeled: "AUDIO_TS" (without the quotation marks).... Visit this site for guides/instructions: http://home.comcast.net/~bbmayo/index.html