Don is planning to do home automation and wants to know if he should use Ethernet in the walls. Leo says sure, he could, but everyone is using wireless these days. Wiring is only really needed for high definition video. Everything else is wireless.
There's no set standard for home automation yet, and if Google and Apple get into it, we could see a standard soon. Leo does recommend the Smart Things Hub, which can handle various standards and make them all play together. It's pretty cool, but it makes Leo nervous because home automation is in it's infancy at the moment. If he already has the walls open, put Cat6 in it. That'll give him all the speed he needs for some time to come.