Ghost/Ambient voltage with Mega 2560

WE are having Ghost voltage issues with this board and was wondering if this is a problem for more intense applications or sensitivity issues when next to other voltages. The board itself was placed ona rubber mat as you seen and had no connections on the board minus what we made contact with on the back at the soder joint (last two videos). Is there an explaination for why this is happening? And why when in contact with the insulated wire (on the insulation) there would be conductivity? Posted below are the videos recording the event while trouble shooting

101311_17532.3g2 (191 KB)

101311_17531.3g2 (190 KB)

101311_17511.3g2 (193 KB)

You've tried to use a LED to see the status of an Input pin?

You need to use a Pull-Up or Pull-Down resistor other wise you are coupling noise into circuit.

Full tutorial on Pull-Up with video, including oscilloscope captures: