SQL Server 2008 File Stream On Existing Table

Hi Folks,
I have enabled the SQL Server File Stream option on a Existing table.

1. Created a GUID Column 
2. Created a File Stream Column 
3. Swapped the Blob Column information into file Stream column. 
4. Dropped the BLOB Column. 

I could evidence, The above Step 3 Process moved out all the Blob Data into an configured Network File Group.

Ex:
Existing BLOB Data Size --> 10 GB 

Once after the completion of above step 4, SQL Server is not freeing up the BLOB occupied Space 10 GB. It should have only few MB's pointer address to the network file Group?

If we create a new table with File Stream data type and insert the existing BLOB data ,Will result few MB pointer Address occupied in the newly created table. We except the similar behaviour for updating BLOB to File Stream in existing table. 

Please advice me.

Thanks 
Narendran

Narendran