Problem with extensions

I was able to rescue a bad dvd with isobuster but it saved with extension .tao (didn’t give me any other option) how can I change the extention to .mpg. Windows XP only lets me change the name but not extension. I can watch the movie in Windows Media player but can’t save in any other format only option - any file -

open the tao with isobuster and drag the mpg out of it ?