The difficulty he said is learning to recognize which stocks are susceptible to this influx of day/night values the most and setting up good option values so that your gains are consistent and your losses are not very much if you're wrong.
Oh, well, if you want to know which stocks are more susceptible to day/night values, look at those who rely heavily on international trade and inventory.
For example: Walmart, Motorola, Toyota, GM, Mitsubishi, BMW, Electrolux, Ericsson, Sony, Rosneft just to name a few off the top of my head.
Best way to determine those types of companies,
Forbes pulls a list out together yearly. Another list you might want to familiarize yourself with is
Inc.com 5000 fastest growing companies.