Interesting quick waterer design. It looks like it would work well for a smaller flock or if one needed to separate a couple of hens. The water does look like it's spilling from the bowl in the picture, which wouldn't work in a coop, but a taller bowl would probably help.
As far as using a balloon for anything, you might want to add a disclaimer saying to ensure that the chickens can't access it in any way because it could be dangerous for them. Also, you want to make sure the latex isn't touching their water at all because I don't think that'd be safe or healthy for them. Besides all of that, cool idea on using a balloon to make something air tight.
