You can use any popcorn in this popper. Of course, don't choose the prepared microwave popcorn. Just the yellow or white kernels that usually come in plastic bags. I use Orville Redenbachers; it comes in a clear plastic container with a screw on lid. I had some very old Orville Redenbacher's popcorn. Instead of throwing it away, I added about 1 tsp water to the container, shook it up real good & put it in the refriegerator. It worked perfectly in the popper; popped big and fluffy. Delicious!
I have seen directions on popcorn that say if you're using it in an air popper to turn the popper on for 1-2 minutes before adding the popcorn. I've had good results using regular popcorn following those directions (heating up the popper before adding the popcorn). Be sure to take off the plastic cover before heating up the popper though, or else it'll get really hot.