SQL Server, attaching a database with Filestream, error 2
It appears you are trying to use the GUI interface to attach the database. In this instance you are going to have to write a T-SQL statement in order to attach it, and let SQL Server know where you put the filestream data as well.

There is a write up here that provides a walk through on doing this, the command the author used in order to attach a database once he had moved the default location of the filestream data for the example database:

USE [master]
GO
CREATE DATABASE [FileStreamDB] ON 
( FILENAME = N'C:\FileStreamDB\FileStreamDB.mdf' ),
( FILENAME = N'C:\FileStreamDB\FileStreamDB_log.ldf' ),
FILEGROUP [FileStreamGroup] CONTAINS FILESTREAM DEFAULT 
( NAME = N'FileStreamDB_FSData', FILENAME = N'C:\FileStreamDB\FileStreamData' )
FOR ATTACH
GO