error: can't access disk

[sassy]

i am trying to open movie files in dvd shrink, was told to use daemon tool lite to mount first. all the movie files are .mpg or .avi or .nzb . there is no option for these types of files other than "all files" which works but then when opening in dvd shrink i get the error message "windows cant open disk, may be corrupt". is there a step i am missing in converting the files? i am new to this and learning by reading how-to's online is very slow