Water will find its own level is what he means in the two tanks or for as many tanks you have connected together at the same level. If the tanks are not at the same level the water will level off in both tanks but they wont have the same amount of water.
I saw another video where the set up looked like yours but he had poor water pressure. Your tanks are on the ground so do you find the water pressure is low or not?
Hi, if I fill 1 tank and do this connection sistem you did, automatically the empty tank will fill with water till both tanks arrive to the same water level?