I believe there is a bug in both the import ripped dvd option and the import ripped bluray option.
1 The ripped dvd option does not perform a recursive folder search. Therefore any dvds stored as groups in sub folders are not recognised.
2 The ripped bluray option does perform a recursive folder search, which is great, but i would expect it to select the index file (index.bdmv) not the 'stream' folder as the file name.