The filter bar seems indeed to search the full path of a file and ignores special characters. You can confirm that if you filter by 'syncmusicmartin', which should return all files below E:\All Music\SyncMusic\Martin Music.
Not sure if this is intended behavior or not, but you can prevent the search bar from returning results in the path of a file if you open the options menu, navigate to Library > Search and untick the Path field.

Please see linked image.

But I finally found how to get similar interface as MM4 (which does not show the artists I did not expect)

http://www.panchdara.com/Images/MM5-SearchQuestion.jpg