Product review (1 stars): In the non vented mode it simply does not work.
I have had this hood installed for about a year now and the filters are as clean as the day they went in. Why ? Because this thing does not work at all if it is not vented to the outside. There are no internal baffles in it to direct the air that it pulls through itself so all the air that  is pulled through takes the  path of least resistance which in this case is around the light bulbs . Almost nothing is pulled through the filters so all that greasy air is just blown back into your house through the exhaust port. If it was vented  through the wall to the outside I'm sure it would work but without that it's just a grease blower.
If you can't vent this to the outside don't waste your money.