It appears that the video has gone missing. Until I can find it and re-post it, you may be interested in Home Made CO2 Reactor, Do It Yourself CO2 Reactor Construction Details, and CO2 Reactor Modifications
The water flows into the top in the big hose, which is coming from my external canister filter. The CO2 is coming from a pair of old juice bottles which have water, baking yeast and sugar in them. This all gets mixed up in all the splashing fun as it goes down the tube with the bio-balls.
At the end of the video you can see my little CO2 monitor in the fish tank – that little bell thingy stuck to the side of the tank. Blue means low CO2, green means good CO2, and if you notice it is more green then it is blue. This is even after the old method of CO2 injection was showing blue, and I hadn’t refreshed my Yeast Bottles yet. This new device appears to be more effective at CO2 Injection then the old feed-it-through-the-canistor-filter method.