\[\sqrt{2\sqrt{5} - 2} \cdot \sqrt{2 + 2\sqrt{5}} =\]
\[= \sqrt{\left( 2\sqrt{5} - 2 \right)\left( 2\sqrt{5} + 2 \right)} =\]
\[= \sqrt{\left( 2\sqrt{5} \right)^{2} - 2^{2}} =\]
\[= \sqrt{20 - 4} = \sqrt{16} = 4\]