A couple thoughts that could have been addressed by the video which I just skimmed (it's late here).
It could be advisable to decouple the light wires from mains wrt radio frequency by using series inductors on both mains wires, so that any RF coming by capacitive or inductive coupling with the antenna wire won't find a low impedance path to a RF ground, which would likely load the transmitter.
One could leave out entirely the holiday lights and their wires and just glue small neon bulbs to the long wire leaving them unconnected; with enough power they could light up by themselves during trasmission, but beware that this would draw power from the transmitter and alter the antenna characteristics.
