Years before Balloon Boy hit the news, the MythBusters were testing how many helium balloons it takes to lift a 3-year-old child off the ground. Watch what happened.

Mythbusters: Balloon Girl

DCFM

the episode with a cable cutting thru a human..
about 1 year ago in Louisville Ky. a young girl was riding a ride at Kentucky Kingdom Six Flag's
The ride called "Super Man Tower of Power", had a cable snap in half, and the whipping of the cable sliced both of the leg's off of the little girl.. I think you should try another test on the cable myth. Jim Oberting

how are you accounting for the lift created by the wind interacting with the balloons, i believe with a steady wind a smaller amount of balloons would be able to lift a child off the ground im really not an expert in physics so i may be wrong but wind catching the balloons and lifting them up might be more effective than a mans arm in counteracting the effects of gravity.

I'm sitting here watching this episode and laughing... they didn't factor the weight of 2700 balloons and whatever string/accessories they will use to bunch them together. Hilarious...

I believe that they didn't really take in count the amount of weight for those strings that the balloons are attached to. I bet that if they used lighter weight strings then it would need less. as well as the weight of the harnest.