The start of this clip may be a little confusing. He's talking about mercury barometers being portable because they are short. If you used water in your barometer it would have to be something like 32 feet tall. Mercury barometers can be under a meter tall.
I don't recommend keeping vats of mercury like the one shown here. Mercury is 13 times heavier than water and quite volatile, the mercury vapors are not good for your brain. Mercury poisoning is responsible for the expression "Mad as a hatter," since mercury was used in the making of felt.