The SMH8165B can be set up to recirculate air into the room from vents located in the front that are concealed from view, or to vent outside from the rear or top of the unit. The installation guide which came with your microwave includes instructions on how to set the unit up to vent inside. All parts necessary for installing should have been included.
Instructions can also be downloaded as a pdf file from this link (see page 20 for step by step instructions for adapting the microwave blower for recirculation): http://ars.samsung.com/customer/usa...
. Please note that these instructions are the same for all Samsung over the range microwaves, and are not specific to any one model.