It won't work with the CO2 bottles we typically use. That's a syphon bottle. It has a dip tube (like the out port on a Corny) going all the way down to the bottom so you always get liquid (as long as there is any). The liquid gets sprayed into the bag and cools to dry ice snow in the process. If you have ever filled a smaller bottle from a syphon or watched while someone did this you will have seen a small amount of dry ice snow form when the cryo tube is disconnected from the target bottle at the completion of filling. The liquid left in the tube gets sprayed through the small space between the connector components as they are separated and some dry ice falls to the floor or is retained in the threads.
From a 50# syphon, which costs $33.46 to fill around here, you might get 20# of dry ice at best (there are several pounds of gas left in the bottle after all the liquid has been drawn off and it is evaporation which produces the cooling that creates the dry ice so lots of gas is lost in the process). So $1.50 a pound certainly isn't prohibitive and the dry ice will be clean. I would think the main problem would be lugging those bottles around. They typically tare at about 120 lbs. Now if you were in a brewery or simialar setting with a 300 # tank which the truck comes around and refills and for which the CO2 would be even cheaper this might be a practical way of getting dry ice in modest quantity.
You actually could get the thing to work on a non syphon bottle by turning it upside down so liquid comes out when the valve is opened. I'm guessing you'd get a pound or 2 of dry ice at most from a 5 pound fill (which is more like a couple of bucks a pound around here AFAIK).
