I notice that you have bubbles coming up from the NEG spoon which would be hydrogen gas (on the whole mostly)
but the video shows no bubbles from the POZ spoon.
In this diagram of the industrial electrolysis of salt brine used to produce chlorine gas and sodium hydroxide (plus hydrogen byproduct) the chlorine gas evolves at the positive terminal. And hydrogen bubbles up at the negative terminal while the water around it becomes an alkaline solution of sodium hydroxide in water.
http://upload.wikimedia.org/wikipedia/c ... mbrane.svgThe cell in the diagram has a membrane which will let little sodium ions thru but won't let chlorines thru.
I think that if you don't have a membrane the chorine that develops at the POZ spoon just remains dissolved in the water and eventually encounters NaOH and reacts to form some sodium hypochlorite and stuff like that. But this seems kind of confusing and irrelevant in the context of a neat science experiment for school kids. Anyway you might tell them that the NEG spoon is the one with extra electrons and when water comes apart some of it becomes H+ which is MISSING an electron.
So that is why the H+ likes to go to the NEG spoon and when it picks up an electron from the spoon it goes back into normal hydrogen and can bubble up out of the brine as hydrogen gas.
So it is the spoon that you touch to the pole of the battery labeled "-" that gets the bubbles.
The spoon you touch to the pole labeled "+" does not appear to get bubbles.
Just my two cents.
Anyway more power to you. Fun to teach kids.