Per some comments at Coffeegeek.com, I figured: "$9.99? Why not?" and bought this popcorn maker at Walgreens ($3.00 mail-in rebate, too!) and tried roasting some coffee. It's a 1200 watt popper. Everyone's favorite, the no-longer-made West Bend Poppery I, is 1500 watts, I believe, and the Poppery II is 1200 watts, I think.
I put 2/3 cup or so of some green unroasted decaf Sumatra beans I had bought at Dunn Bros Coffee a few weeks ago into the popping chamber, and used an empty canned green beans can for a chimney. You need the chimney because as the coffee roasts, it gets lighter in weight, and the spinning/blowing of the popper will propel the beans up and out of the popping chamber unless you have a long chimney.
(To make the chimney, I removed both ends of the can with a can opener and cut about eight 1"-long slashes around one end so I could compress the end diameter to fit into the opening of the popcorn maker - a soup can was too narrow for this popper.)
The plastic cover for the popper sits closer to the popping chamber than some others I've seen, and I was afraid the heat would melt it, so I roasted the coffee with the cover off and the chimney extending the height of the chamber.
I then went outside and plugged it in. It was apparently too cold outside, though, because after several minutes, while the beans had darkened somewhat in color, they were not roasting or smoking or cracking.
So I brought it inside and continued the process by the stove-top ventilation fan, and the beans started darkening in color and even cracked a bit and started getting a bit of an oily sheen. There was no chaff (decaf beans don't have chaff, but regular beans do - lots of it, apparently, which is another reason to roast outdoors so it doesn't blow all over the house) and only one bean caught on fire. I never did get any smoke, but I tasted a bean when it was looking pretty dark, and since it seemed done, I turned off the popper and cooled the beans outside by stirring them with a wooden spoon in a metal colander.
We ground and brewed the beans, and they tasted pretty good - a medium-tasting roast (though they looked darker than that), with a lot of "foaming" in the AeroPress since I didn't give them a day to degas.
I did another batch at about 10:15 p.m. indoors. I didn't get any smoke this time, either. Maybe it's the roasting chaff that creates the smoke, and since there is hardly any chaff on decaf beans, there is also little or no smoke. It took longer than I expected, and I couldn't hear the second crack, but the beans are fairly dark. I put them in a plastic bag for grinding and brewing in the morning.
The instructions say to use no more than 1/2 cup of popcorn kernels to prevent overheating. I tried roasting 1/2 cup of beans with the popcorn cover on, but I still had beans popping out of the cover, so it seems that I need to use the chimney without the cover. Also, 2/3 cup of beans seems to roast fine without overheating the popcorn maker.
The following isn't the best video, but it shows and explains the process. It doesn't show the inside of the correct popper very well, though, so you can't really see how the vents are on the side of the chamber, but if you examine hot air corn poppers, you'll easily see what it means for the vents to be on the side of the chamber.