Cu(NO3)2(aq) + 2NaOH(aq) ---> Cu(OH)2(s) + 2NaNO3(aq)

Cupric nitarate solution reacts with aqueous sodium hydroxide and produces blue cupric hydroxide and sodium nitrate.

By getting down to eye level Andrew is sriving for accuracy by seeking to find the exact measerment of the liquid to pour into the graduated cylinder.

DOUBLE REPLACEMENT
It is a transfer of electrons and these particular products formed because Cu has a positive 2 charge and NO3 has a negative 1 charge. When mixed with NaCl (both Na and Cl have a positive and negative 1 charge) the electrons transfer and form the products.