Here is a new test that will prove my point. Using the same 4 wires in your video tape them all on their own seperate piece of tape. The only way for the light to go on is if power is sent through the melamine to the other wire. (keep the positive connected to each other and seperate the negative).
if the insulation on the tape and flex watt breaks that's where the problem is. Why risk it?
if the wire is on all separate pieces of tape it will not conduct electricity to the light (obviously) and the electricity will not pass through the wood.