He means that it isn't possible to create infinite lava pools by creating a 2x2 pond and putting lava in the corners, like water.
Yes, exactly. I don't usually like exploiting things, but if I can exploit one liquid block type, why not the other? Were infinite Lava pools abused heavily back a few updates ago, because I seem to remember having a + shaped Lava pool, taking the middle part out, and the four Lava blocks around it filled it in by themselves.