You could get a ton of Amateur Radio operators around the world interested in Bitcoin if you were to put an APRS beacon on the balloon. You will need to get an amateur radio license to legally transmit the beacon.

http://en.wikipedia.org/wiki/Automatic_Packet_Reporting_System
http://www.aprs.fi

I'm curious what you will be using to transmit the live video data from the balloon? A cellular data connection will not work after ~5000 feet for a variety of reasons. I'm pretty sure your only two options would be to use a satellite data connection (which would be very expensive for live video), or broadcasting the video with an Amateur Radio ATV transmitting setup (again, which you would need a ham radio license for).

If you have any questions, shoot me a PM.

source - I'm an amateur radio operator

73!