What I meant was that he recommends that the average investor should invest in the S&P 500 or total US market only. He doesn't seem to think people should invest their money abroad.
There's a decent argument that American companies are multinational and therefore already exposed to foreign markets. I don't subscribe to that, but it's not totally unfounded.
That strategy would have lost out in the rise in uk stocks due to the drop in the pound
That rise only exists when you look at the ftse denominated in GBP not USD.
A lot of the FTSE 100 companies do look at how RDSB (Shell) Oil is denominated in $