You can see in the video that there is water inside the bottle that is turning the bright LED on when it is touching the terminals during shaking. Because the water does not completely leave the wire terminals (unless you leave the device on the table for a long time) the bright LED is not completely turning off.

This Instructable shows how good the water is at conduction electric current.

You can see in the second photo that I attached the circuit to the sculpture with a small piece of rope. Do not use a coil. You will short the circuit. However, you can use plasteline or blue tag.

Supplies

Components: 9 V battery, 9 V battery harness, 1 kohm resistor, a small piece of matrix board, small plastic bottle (CD/DVD cleaning, acrylic paint, toothpaste, sunscreen, cream, ketchup or glue), blue tag or plasteline, a few bright LEDs (you only need one but I burned one - the one you see in the video), coil or metal wire (to make the arms and legs), threat or small piece of rope to attach the circuit to water bottle (you only need this if you do not have enough blue tag).

Components for conduction: wires or coil.

Tools: wire stripper (you only need it for the wires) or stone (to erase the coil insulation layer - you only need it if you are using coil), scissors, soldering iron (optional).

Optional: electrical tape or masking tape, solder.

Step 1: Build the Sensor

You can see in the first photo that I used a small stone to erase the insulation layer to allow conduction when the water hits the terminals.

In the second photo, I covered the two-wire terminals with solder to reduce the rusting effect due to water. Unfortunately, the second photo is blurry because my camera is not good at capturing close up objects.

Step 2: Build the Circuit

The two terminals in the circuit will be dipped in the water when the bottle is lying down or being shaken.

You definitely do not need a high power resistor that you see in the photo. I used a high power resistor because it was yellow. The local shop (Jaycar Electronics) sells low power resistors in dark blue colours and I cannot really see the colour codes in blue resistors because they blend with the resistor's dark blue colour.

You can wire maximum current calculations in during short circuit:

Imax = (Vs - Vled) / R1 = (9 V - 2 V) / 1000 ohms = 7 mA

LED should be supplied with a current of 10 mA. However, I have chosen a 1 kohm resistor in case you connect this circuit to 12 battery. Increasing the supply voltage to 12 V will raise the short circuit current from 7 mA to 10 mA.

Warning: Keep in mind that 12 V can supply high currents because they need to drive the electric car starter motor during ignition. Thus could be very dangerous if the battery-electric terminals are shorted.

I used https://easyeda.com online circuit simulation and PCB (printed circuit board) design website to draw this circuit.

Step 3: Fill the Water Bottle

Make sure that the water bottle is initially empty and clean. The dirt in the bottle can damage or stick to the electric terminals.

The small water bottle only needs to be from a quarter to a third full. You can see the two wire terminals sticking out.

Step 4: Testing

The first video shows a waterfall man without a 1 kohm resistor. That is why I burned the LED because the two wire terminals eventually touched and the bright LED received the whole battery voltage of 9V instead of the maximum 2 V that it can handle.

However, the last video is showing that the bright LED has sufficient brightness even with a 1 kohm resistor and the conducting water in between.