The pdf on the Flinn site has good safety precautions. Like putting the "snake" on the bench and lighting it from a distance with a candle on a meter stick (after turning off the gas) rather than lighting it out of your hand. Since so many people just follow the pictures and don't read, you really might need to include those precautions in the video itself. Smaller rooms, low ceilings and mediocre air exchange could lead to some bad results. Worst case scenario might be reaching the explosive limit of methane in air. If the column is fairly high the bubbles could lean too close to the person's face as they are lit. I really think this is a demo that should not be taken on the road. Do it in a large lecture hall (at a college or university most likely) with high ceilings and good ventilation and no volunteers from the audience. And don't keep the gas on for such a long time. Make your column, turn off the gas and talk. Take off and discard the column of bubbles, make a new column, turn off the gas and carry the column over to the bench for lighting. And not too tall a column lest it bend over toward you, especially if you just must light it from your hand. The whole "look at the video and try to replicate without knowing the potential problems" thing is a common phenomenon in our YouTube culture.
Sandra Koster
