You can see in the first part of the video that the mainboard and all components  except the power supplyare filled up with oil. Now you are probably wondering how is this possible:

Oil doesn’t conduct electricity, and  in the video they are filling the components up with it. Oil has the great feature that it is dense and electronic components will work without any problem. If we look at it from an other perspective it is the perfect cooling system, it doesn’t need maintanance and it will surely do the job at its best.

An oil is any substance that is in a viscous liquid state (”oily”) at ambient temperatures or slightly warmer, and is both hydrophobic (immiscible with water, literally “water fearing”) and lipophilic.

If you have some extra time feel free to do it, but remember to keep your power supply dry and in a sealed area.