They didn't show what would happen to a MB without it - which I would like to see.
For all we know, others might well work fine at least short term, and the only impact is parasitic capacitance.
They are probably using distilled water, which most of the motherboard components wouldn't care about anyway. They should re-do it with salt water.
http://www.youtube.com/watch?v=qXB5jlODJSs
When has anyone filled their loop with salt water? Unless you are pouring sweat or swimming with your motherboard this shouldn't be an issue. 😛
Think people.. if a motherboard can be made waterproof then a graphics card can be too. All they need to figure out is how to make the pins waterproof and they are set to make a commercial coolant submerged PC.
But of course it is easier to drool&bash something than ponder a bit.
You can tell the amateurs filling up this thread who think their crappy H100 cooler is impressive. When you put on your big boy pants and upgrade to real cooling...the kind that goes sub ambient, condensation becomes a problem that this would solve.